History Main / BluffTheImpostor

---> '''Sophie:''' I'm so sorry. It was a beautiful ceremony.

* The ''TabletopGame/{{Pathfinder}}'' adventure path ''Shattered Star'' has a written-in example in book 2, ''Curse of the Lady's Light''. Thanks to an instant-death trap interacting weirdly with a clone spell, it is possible for a player character to end up inhabiting the body of a clone of [[PrecursorVillain Runelord Sorshen]], and the main antagonist of this book is a demon who has shapeshifted into Sorshen and genuinely believes she is Sorshen. If a player uses this to their advantage and attempts to impersonate Sorshen to bluff the Gray Maidens working for the demonic Sorshen, but they fail a Bluff check and thus arouse the Gray Maidens' suspicions, they ask "Sorshen" what happened to the magic shields she promised. If the player impersonating Sorshen indicates that they believe such a promise was made, or if they fail a second Bluff check, the Gray Maidens confirm their suspicion that the Sorshen they are addressing is an imposter and attack.

* A woman named Shellie Kepley became concerned because she could not reach her father, Paul Gruber, despite the fact that he continued to send her greeting cards for various holidays and events. However, she had noticed that his signature was different. The next time she called him and left a message, she reminded him of her son's upcoming birthday, as well as the money he had promised. Sure enough, she promptly received a card with a check for $25. However, this only ''confirmed'' her suspicions that something was wrong, as it was NOT her son's birthday, nor had she asked him for any money, both of which her father would have known. Police eventually found that a local handyman, Darryl Kuehl, had befriended Gruber before murdering him to gain access to his bank account and was keeping up the illusion of him being alive by continuing to pay his bills and send letters and cards to his family.

* In ''Defenders of Stan'', ButtMonkey Stan has a death ray pointed at two guys. One is his {{jerkass}} brother, Ted, and the other is his brother's evil robot clone. Stan says, "I love you, Ted." The robot clone says that he loves him too while his brother laughs and calls him gay.

'''T-1000:''' Wolfie's fine, John. Wolfie's just fine. Where are you?\\

* ''Manga/DeathNote'': L does this to Light quite a bit to see if he slips up by saying something only Kira would know. For example, showing him three suicide notes Light had some criminals write and seeing if he can find the secret message Kira inserted into them to taunt L, who has intentionally given Light the notes in the wrong order. However, Light is also a supergenius, and quickly figures out what L is up to, and hence doesn't expose himself (by putting the notes into the right order or being surprised when L introduces a fake note to the mix). Partially subverted anyway. It takes a bit for Light to realize that the fake note makes sense, and L ends up being slightly more suspicious of Light than he was before the test.

* In UsefulNotes/WorldWarII: A variation for those on watch both used and inverted this system: The guard would state "The Land of the Free," to which an American would reply "And the Home of the Brave." Then the guard would state "The Terror of Flight," to which a German would reply as "And the Gloom of the Grave"... Every American soldier would [[TrustPassword know the first verse of their national anthem]], but only a spy [[INeverSaidItWasPoison trying too hard to pass as one]] would know the ''third'' verse.

* ''Series/{{Leverage}}'': Sophie is nearly outed when the mark asks her if she's familiar with a certain person. Nate smiles and tells her (on her earpiece) to reply that the man is dead, which satisfies the mark. This is a bluff on Nate's part, though, as Hardison only confirmed the information several seconds later, which would've been too late for Sophie.
** For her part, Sophie tries to be as vague about it as possible invoking NeverSayDie:

** Also, the Gileadite trap for Ephraimite spies in Judges 12. The Ephraimites were unable to pronounce "sh" properly, so the Gileadites used the word "shibboleth" as a password -- if you couldn't make the sound correctly, and rendered the word "sibboleth", it was definitely not your lucky day...

%% If the bluff "fails" because the target is genuine, that is *not* a subversion--it's a straight example and belongs in the above section.

* In the ''WesternAnimation/SpongeBobSquarePants'' episode "Imitation Krabs", [=SpongeBob=] quizzes Mr. Krabs and an obvious robot impostor ([[PaperThinDisguise complete with smoke-spewing exhaust pipes and clanking gears]]) operated by Plankton on three things "only the really real Mr. Krabs would know". The first two questions are things that anyone who frequents the Krusty Krab would know (like "How much does a Krabby Patty cost?") so the imposter jumps in with the right answers. The last question is completely bizarre and nearly impossible to follow so Mr. Krabs fails on it, "exposing" him as the fake. Of course, it ''is'' [=SpongeBob=].
** The third question is actually a trick question if you stop to think about it. Earlier in the episode, Mr. Krabs said to "never discuss the [[VerbalTic formuler]]". [=SpongeBob=]'s question was about discussing the formula under certain circumstances, "outing" him as the impostor.

Related to YouJustToldMe and SpotTheImposter. May involve SpySpeak. See also CoverIdentityAnomaly, PullTheThread and SomethingOnlyTheyWouldSay, for when the impostor says something that breaks his or her cover, intentionally or not. Contrast INeverSaidItWasPoison and TrustPassword. May involve ExasperatedPerp. Compare BluffTheEavesdropper.

[[folder:Anime & Manga]]
* A rare case of this happening to the protagonist occurs in ''Manga/{{Arisa}}''. Tsubasa is disguised as her titular (comatose) [[TwinSwitch twin sister]] in an attempt to figure out the true identity of "the King", a figure causing all sorts of bullying, manipulation and general chaos at Arisa's school. At one point, she receives a message from someone she strongly suspects to be the King, telling her to meet them at the place Arisa's boyfriend took her on her birthday. Tsubasa can't find that detail in Arisa's letters, so she feigns memory loss from a stay in the hospital to get the boyfriend to tell her. [[spoiler:She was doomed from the start, though, since Arisa's boyfriend ''is'' the King and has known about the switch the entire time.]]
* Both in ''Manga/CaseClosed'' and ''Manga/MagicKaito'' [[note]]Both series take place in the same universe with storylines overlapping[[/note]] has a flashback episode which Kaitou Kid encounters Shinchi Kudo. Kaitou Kid disguised himself as a regular police officer to try and steal the clocktower. The police department know Kaitou Kid is a master of disguise so they ask everyone their name and badge number. When Kaitou Kid is questioned, he gives the person's name and badge number, then the officer ask what their ID number is, which Kaitou Kid gives correctly, and that tips officers that he is Kaitou Kid. Shinichi told the officers to ask for the ID number as most people do not know their ID numbers and figured Kaitou Kid would answer the question.
* In ''Manga/DescendantsOfDarkness'', Hisoka suspects that Tsuzuki is possessed by a demon and tells him, as usual, to bring something to eat for their boss Chief Konoe. He "reminds" Tsuzuki that Konoe hates sweets, and when Tsuzuki falls for it, he knows it's an impostor. (Konoe has a notorious SweetTooth.)
* In ''Anime/DigimonFusion'', episode 39, Kiriha suddenly remembers to return a Digimemory he borrowed from Taiki, and Taiki agrees. Except that the borrowing never happened, and Kiriha hands over a small explosive device that ruins Splashmon's impersonation of Taiki.
* Love of ''Anime/FreshPrettyCure'' bluffs an impostor of her mother by switching her and Setsuna's presents and thanking her for the wrong one.
* In ''Manga/FromEroicaWithLove'', Major Eberbach tests if a guide who called him is a KGB spy by asking her about a fictitious aunt. When the guide gets confused, he concludes she's no spy, because a spy would've pretended to know the woman.
* ''Manga/FullmetalAlchemist'': Riza Hawkeye and Roy Mustang are hunting down the shapeshifting Envy and get separated; when they meet up again, they exchange a few words, then start off looking for Envy... until Hawkeye puts her gun to Mustang's head. It looks like Hawkeye might actually be Envy, until...
-->'''Mustang:''' What are you doing, Lieutenant? Don't you know who your gun's pointed at?\\
'''Riza:''' ''Who?'' Don't make me laugh. When we're alone [[ShipTease the Colonel always calls me by my first name, Riza.]]\\
'''Envy:''' [[OhCrap Grk!]] ''(dives away, transforming back into Envy)'' So you two are that close, are you?\\
'''Riza:''' ILied. *BANG* But thanks for falling for it. [[BadassBoast Now you can do me the favor of dying.]]
* In ''Manga/{{Guyver}}'', protagonist Sho is handcuffed to love interest Mizuki so he can't bio-boost without blasting the broad to bloody bits. Hearing half a warning that she might not be who she appears to be, Sho laments that this had to happen right after Mizuki's birthday. She agrees, and her cover is blown because Sho knows her birthday is later in the year.
* ''Manga/JojosBizarreAdventureStardustCrusaders'':
** During an attempt to find an enemy Stand user, Jotaro claims that Stand users have blood vessels on their nose that stand out when they inhale cigarette smoke. All of his allies reach for their noses... as does the captain of the ship they're on. Then Jotaro adds that he was bluffing, and his suspect drops the innocent act.
-->'''Polnareff:''' You can't be serious, Jotaro!\\
'''Jotaro:''' You're right. I lied. But it looks like someone fell for it.\\
'''Captain Tennile:''' [[OhCrap Ahh!]]
** This happens again later to Oingo who uses his Stand to be disguised as Jotaro himself, albeit unintentionally. His plan to kill Jotaro goes horribly awry when Jotaro's friends all force him into their car and, because they're bored, repeatedly request "Jotaro" to perform various stunts of increasing danger (such as holding multiple lit cigarettes inside his mouth), each time saying that Jotaro is good at this sort of thing. Oingo pulls them all off and so Jotaro's friends never once suspect he's a fake, but Oingo gets so nervous that he decides it's not worth the risk of self-mutilation and, claiming he needs to take a dump, escapes from the car as far as he can run.
* Done heartbreakingly in ''Manga/{{Karin}}'' (with a bottle of Tabasco sauce) towards the end of the manga, to determine if the title character's sister has matured to the point where scheduling differences now leave her without any daywalking family. [[OurVampiresAreDifferent Adult vampires]], you see, have no sense of taste.
* Happens in ''Manga/KOn'': Ui has disguised herself, rather convincingly as Yui until she slips polite speech which starts to undo her cover. She tries to deny it but Azusa demands Ui call her by her [[InSeriesNickname nickname]].
* In ''Manga/LoveHina'', Keitaro lies about being a student at Tokyo U, so Naru asks him about the miso-boiled lobster they serve in the cafeteria. Keitaro babbles on for a bit about how it's his favourite food that he can't start the day without, before Naru tells him that there is no such thing as a miso-boiled lobster.
* ''Manga/{{Naruto}}'':
** Sasuke came up with a very long and convoluted "[[TrustPassword password]]" for his two teammates to memorize in case they ever needed confirmation of one another's identity. Naruto leaves to go to the bathroom, and when he comes back, Sasuke asks him to code in. Naruto repeats it back perfectly... and Sasuke decks the imposter, declaring that the ''real'' Naruto would [[IdiotHero never have been able to remember something that long]].
** Later, the Mizukage does this quite expertly, although her victim is not an impostor, but under control. [[spoiler:Ao, possessed by one of Danzo's men, encounters the Mizukage and Chojuro, apologizing to the latter for getting into a position in which he needed help, then asks the Mizukage to remove the seal on his eye. She then points out that Ao would not apologize to Chojuro, and he'd know the sealing tag could not be removed, then punches him when he [[TooDumbToLive calls her]] [[BerserkButton an old hag]], thus restoring Ao to normal]].
** Naturally, Naruto is [[IdiotHero too stupid]] to pull one of these himself. In one filler arc, he, Hinata and Kiba have to deal with impostors copying their every facet. So naturally when trying to identify the real Hinata, rather than asking a baited question like, "Hey, Hinata, how did you defeat Neji during the Chuunin exams?" he inverts the trope, asking, "What is the name of Hinata's father?" -- a question any good imposter would study beforehand, but one that Naruto himself didn't know the answer to, making it utterly useless even if the imposter didn't know!
** Sakura pulls one of these off [[spoiler:against Zetsu, who was impersonating Neji during the current world war. Or rather, Zetsu does it to ''himself''. When Sakura mentions that Tonton (Tsunade's pig) is being looked at for a twisted leg, [=Zetsu!Neji=] says that it's better to have injured her leg than her hand, then asks if Tonton can still weave signs. Sakura says yes, but then when [=Zetsu!Neji=] comes closer, she pounds him into the ground and tells him that Tonton's a pig]].
*** This is actually quite a clever application by the writers considering that the Zetsus seem to learn a fair amount about the people they impersonate. Neji's team mate is Tenten. It's not such a stretch to think that Zetsu was simply trying to be too clever.
** Episode 333: The imposter shows up in front of the real Naruto Uzumaki and declares that he is Naruto Uzumaki. Until Naruto said that [[ConfrontingYourImposter he was the real one]] and the imposter got curbstomped
* In ''Anime/{{Obsolete}}'', during a demonstration of their uparmored Exoframes to Rei Miyajima, Captain Wangchuk of the Indian Army Special Warfare Brigade Ladakh Scouts demonstrates a "traditional Indian exercise" while operating an Exoframe. [[spoiler: At the end of the episode, Wangchuk reveals to a subordinate that the exercise was actually a common Japanese calisthenic routine, and the fact that the Miyajima didn't immediately react or recognize it confirmed Wangchuk's suspicions that Miyajima was not from Japan, much less seconded by the Japanese Ground Self-Defense Force as he claimed to be.]]

[[folder:Comic Books]]
* ''ComicBook/BuckDanny'': One story has Buck shot down deep in enemy territory, stuck in a tree in the middle of a swamp. A plane is sent out to rescue him, but the enemy commander can hear their transmissions, and instructs his men accordingly (when Buck shines a light to mark his position for pickup, the soldiers do the same). After the Vietcong show they're listening in by flashing their lights as often as Buck, Sonny tells Buck to use the winning score of the last basketball game played on the Entreprise.
* In ''ComicBook/DoctorStrange: The Oath'', Doctor Strange encounters a demonic entity who tries to convince Strange that he is facing one of his most powerful foes, Dormammu. Strange, suspicious of Dormammu's sudden arrival, asks him, "So where is Umar, your rapscallion of a brother?" When Dormammu answers, "He is none of your concern," Strange has his answer; Umar is Dormammu's ''sister''.
* In ''ComicBook/InfiniteFrontier'', DEO agent Cameron Chase confronts a returning Captain Atom on working with the DEO. Atom refuses as Chase brings up their past working together and Atom says he remembers it well but they've both changed since then.
-->'''Chase''': Yeah, but that's the thing...''(raises her gun)'' You and I have never met before.\\
'''"Atom"''': Dammit. Oldest trick in the book.
* In ''ComicBook/OldManLogan'' #25, Logan stops at a diner he frequents. He notices the staff is different, and asks the waitress what happened to Lexi. After the waitress responds by saying Lexi took the day off, Logan grabs her and reveals nobody named Lexi has ever worked there. It's then revealed that the real staff has been [[KillAndReplace killed and replaced]] by members of the [[ComicBook/TheIncredibleHulk Hulk Gang]].
* Katie Power from ''ComicBook/PowerPack'' once attempted this with her future self.
-->'''Past Katie:''' Who was my first boyfriend?\\
'''Future Katie:''' [[ComicBook/FantasticFour Franklin Richards]].\\
'''Past Katie:''' Wrong! It was a trick question. [[GirlsHaveCooties Boys are gross!]]\\
'''Future Katie:''' Give it a few years, honey. You'll change your mind.\\
'''Past Katie:''' Ewww.
* In ''ComicBook/{{Ronin}}'', Peter's suspicions of "Taggart" not being what he seems are confirmed when he doesn't react when Peter claims that his wife Casey accompanied the two on a trip, when she did not. [[spoiler:And when Virgo doesn't react either, he knows she's in on it too.]]
* In a ''ComicBook/SpiderMan'' story from when the Parker family lived in [[ComicBook/TheAvengers Avengers Tower]], Chameleon walks in disguised as Peter. Aunt May notices something is off right from the start, and hits him with three of these, starting by offering him oatmeal cookies ([[DoesNotLikeSpam which Peter hates]]). Once he's eaten the (drugged) cookies, she explains how badly he screwed up just before he passes out.
* In the ''ComicBook/Team7[=/=]ComicBook/{{Weapon X|1991}}'' crossover, the two squads meet in an underground base they were both tasked with blowing up. At gunpoint, they ask each other sports questions to find out if they are Soviets. Amusingly, Wolverine (a Canadian) asks a hockey question, which would probably be more easily answered by a Russian than an American.
* ''ComicBook/WonderWoman1987'': ComicBook/WonderWoman and ComicBook/CaptainAtom are out to rescue ComicBook/SteveTrevor from shape-shifting Durlans. They're separated and "Atom" comes to Diana to say he found Trevor. Suspicious, Diana asks if he also found Captain Nate Adam." When "Atom" says he did, Diana knows this is a Durlan...as Nate Adam ''is'' Captain Atom.
* ''Franchise/XMen'': Visiting the X-Mansion, Banshee starts to sense something is wrong. Seeing Bishop and Gambit, he makes an offhand remark of how "now that the Professor is walking again," he's been busy. When both men agree, Banshee knows they're imposters as Professor X is still in his wheelchair.

[[folder:Fan Works]]
* ''Fanfic/AllAssortedAnimorphsAUs'':
** In "What if Elfangor and Loren raised Tobias?", the Animorphs (wrongly) suspect that Tobias' parents are Controllers. Marco tries to get them to slip up by asking them about [[WeaksauceWeakness instant maple and ginger oatmeal]] and what they do in their spare time.
** In "What if Tom was infested by a member of the Yeerk Peace Movement?", it's mentioned that Marco spends over an hour asking Tom and Aftran questions in an attempt to prove that Tom has gone voluntary and teamed up with a Yeerk pretending to be Aftran as part of a plan to kill the Animorphs (he hasn't).
* In the ''Manga/DeathNote'' fic ''Fanfic/ACureForLove'' Light does this when Near calls him pretending to be L:
-->'''Light:''' L?\\
'''Near:''' Kira?\\
'''Light:''' [[IKnowYouKnowIKnow Wouldn't you know if I am Kira or not?]]\\
'''Near:''' [[OpenMouthInsertFoot All voices sound very similar.]]\\
'''Light:''' You're not L.\\
'''Near:''' I assure you that--\\
'''Light:''' No. You're not. Where is L?\\
'''Near:''' This ''is'' L.\\
'''Light:''' Put L on or this call will end in record time.\\
'''L:''' Alright, Kira-kun. Since you can see past voice masks.
* ''Fanfic/TheDarkLordsOfNerima'': [[spoiler: When Ekim takes control of [[Manga/RanmaOneHalf Ranma's]] body, with the intention of attacking [[Anime/SailorMoon Sailor Mercury]], she intercepts him and, suspicious of his behavior, asks why he'd want to talk to her since she was the one who destroyed the "summoning artifact". Ekim responds that he began to respect her after that, which confirms her suspicion that it's someone else, since Ranma would know it was Sailor Moon who destroyed it.]]
* ''[[http://archiveofourown.org/series/82162 Stars From Home]]'': Scott uses this when he believes Raven is impersonating Alex; he is already convinced, but tries to prove it to Charles by having Alex describe the day Scott was born. [[spoiler:It works. Alex appears several years older due to experiments keeping Scott young. So Alex couldn't remember the day Scott was born--because it happened before Alex himself was born.]]
* Due to an earlier case of OneDialogueTwoConversations, Ranma is convinced Mandy and her friends are his handlers in ''[[http://cartoon.adult-fanfiction.org/story.php?no=600095039&chapter=4 How I Learned to Love the Wild Horse]]'' but eventually notices that they're asking questions they should already have the answer to. He doesn't really get it until they ask about his sister, at which point he asks which school his sister goes to. They make a decent guess but if they were his handlers from WOOHP, they'd know he doesn't have a sister.[[note]]Ironically due to Britney giving bad intel, his actual handlers don't know either.[[/note]]
* In the ''WesternAnimation/TheLoudHouse'' fanfic ''Fanfic/StoriesAndTalesFromDimension63'', chapter 21 Lisa uses this trick to determine if the "Lincoln" in her house is an imposter. She asks him how taking the Glow Serum (from the first episode of the series) she invented a while ago felt, and “Lincoln” answers it tasted like vinegar. The real Lincoln never took the serum (Lisa gave it to Luan after all) and thus shouldn’t know about this.
* ''Fanfic/DistortionsSymphogear'': While Hibiki's family is being moved to by some people who claim to be from [=SONG=] agents to safety,Hibiki's grandmother asks some questions about how Hibiki has been doing; like has the media been keeping her from getting enough sleep due to the media circus or how has she been eating. Their answers; that the media have been keep her up when Hibiki [[HeavySleeper could sleep through a tanker truck exploding]] and eats three meals a day when she [[BigEater eats much more than that]], tell her that they know nothing about Hibiki and aren't what they say they are.
* ''Fanfic/PrincipalCelestiaHuntsTheUndead'': Celestia and Luna suspect that Sunset has been replaced by a changeling, even though she passed the TrustPassword. Celestia struggles to think of something else to test her on, something small enough that a changeling wouldn't have been able to research it, but important enough that Sunset would never have forgotten it. Luna decides to come at it from a different angle--a lie that the real Sunset would never accidentally mistake for the truth. Then she walks up to "Sunset" and says she forgives her for having sex with Celestia. Since Celestia has [[ParentalSubstitute basically adopted Sunset by this point]], it's very obvious when the changeling tries to play it off.
-->'''Luna:''' ''[to Celestia]'' You're just mad because my plan worked.
* In ''Literature/HarryPotterAndTheGobletOfFire'', we know that Barty Crouch Jr. killed his father after Crouch Sr. saw through his Polyjuice impersonation of Alastor Moody. ''[[https://archiveofourown.org/works/23082325/ Of Lacewing Flies and Treacle Tarts]]'' shows us why: Crouch Jr. addresses his father, and tells him he would've been a fair Ravenclaw student like himself. Crouch Sr. immediately points out Moody was actually a Gryffindor student when he attended Hogwarts.
* When Jake realises he's been [[PeggySue sent back in time]] in ''Fanfic/WhatTomorrowBrings'', he tells Tom that he hopes to get his spot on the basketball team. Tom says [[OOCIsSeriousBusiness he quit]], confirming Jake's suspicions that he's still being controlled by Temrash 114.

[[folder:Films -- Live-Action]]
* In ''Film/AloneWithHer'', when the protagonist, the girl he's secretly spying on/manipulating, and her best friend are having lunch, the best friend asks him if he'd been to a particular fashion district in Seattle (since he claims to be from Seattle). He says yes, and once he's out of the room, the best friend reveals that she made the fashion district up.
* In ''Film/AmericanPsycho'':
-->'''Lady:''' Did you see the ad in the ''Times''?\\
'''Patrick:''' Uh, yeah.\\
'''Lady:''' There was no ad in the ''Times''.
* In the Creator/JetLi film ''Film/BlackMask'' one of the SuperSoldier villains has infiltrated the police and gotten into the unit led by Li's best friend. Late in the movie Li's friend begins to notice the suspicious behavior from the infiltrator, and begins casually asking the infiltrator a few questions, like how long he's been on the force (about a year) and which department he was in before transferring into this unit. In response to these answers, Li's friends says that means the guy must have served with Captain Chan, and talks about how nice a guy Chan is. When the infiltrator agrees with this he's immediately shot: "Chan died four years ago, and he was a real prick!"
* In ''Film/{{Captain Marvel|2019}}'', after Nick Fury's boss calls him "Nicholas",[[note]]Fury having mentioned earlier that no one ever uses his first name[[/note]] Fury realises he's been replaced by a Skrull. He confirms it by claiming their current situation is "just like our mission in Havana",[[note]]which never happened, Fury having also mentioned that he only did missions in cities starting with the letter "B"[[/note]] to which the Skrull agrees. [[spoiler:Gets a CallBack later on when the same Skrull, now an ally and disguised as a Kree guard, uses the same line to let Fury know who he is.]]
* ''Film/{{Darkman}}'': The villain comments to the title hero, while the hero is in disguise, that he would hate for his (the person who Darkman is impersonating) wife and kids to miss out on such a "great role model." When Darkman answers that they do look up to him, the villain casually notes that he doesn't have any kids, and nailguns his hand to the wall.
* ''Film/DarkmanIITheReturnOfDurant'': Durant (the villain) suspects that Darkman is masquerading as Ivan, and to make sure he makes a comment about not having to leave someone's body behind in Saskatoon. He was refering to an earlier conversation, where he's talking to the woman in question in Ivan's presence and states that they'll be burying her in ''Saskatchewan.''
* From ''Film/{{Dave}}'', where Dave has been hired to stand in for the President after a stroke renders him comatose.
-->'''Ellen (The President's Wife):''' Reminds me of when you were in the state legislature.\\
'''Dave:''' Yeah... me too.\\
'''Ellen:''' You weren't in the state legislature. ''(stands up and offers her hand)'' Hi, I'm Ellen Mitchell. Who are you?
* In ''Film/DiamondsAreForever'', Mr. Wint and Mr. Kidd [[RoomDisservice pretend to be room service]] and serve Bond and Tiffany diner. After they serve the drinks, Bond remarks he would have liked to drink a claret. Mr. Wint apologizes and says they ran out, then Bond points out the drink they served ''was'' a claret.
* This trope shows up in ''Film/{{Eraser}}'' when Lee Cullen, the witness John Krueger (Arnold) is assigned to protect, gets picked up by an enemy agent posing as John's ally (when John was betrayed and on the run). Remembering John's advice to her to "trust no one" and that [[IWorkAlone John only works alone]], Lee then asks the fake agent to perform John's SecretHandshake, before shooting the imposter in the kneecap and running. Cue a bunch of mercenaries showing up and pursuing her.
* ''Film/EyesWideShut'': This is how Bill is called out during the orgy sequence. He's asked for the house password in addition to the admittance password, which he says he forgot. Later on, he's told that there was no house password.
* In ''Film/FaceOff'', FBI agent Sean Archer infiltrates prison perfectly disguised as his arch-nemesis, Castor Troy, in an attempt to discover the location of a bomb from Castor's brother, Pollux. Ever paranoid, Pollux quizzes Archer on what medication he takes, but Archer is so obsessed with Castor that he is able to answer correctly.
* In ''Film/GodzillaFinalWars'', to prove Daigo is an imposter, Anna presents what is apparently Daigo's dog Clint. "Daigo" cannot guess the dog's name, and eventually, Anna reveals it wasn't Clint at all, but her own dog Candy.
* Major Marquis Warren and Bob the Mexican go back-and-forth with each other throughout the first half of ''Film/TheHatefulEight''. Warren takes an instant dislike to Bob and doubts his claim that Minnie is visiting her mother and left Bob in charge while she's gone. Eventually Warren stops pressing the point because Bob manages to correctly respond to the traps that Warren lays out to catch him (The first one being able to identify the type of tobacco Minnie smokes) [[spoiler:It turns out that Bob ''is'' lying, and had helped kill Minnie before Warren arrived. He was able to dodge Warren's questions because he heard Minnie talk a bit before the rest of the gang killed her, but he still gets shot, because Minnie was notoriously racist towards Mexicans and would not let Bob in if she knew who he really is]].
* ''Film/JurassicParkIII'': Paul Kirby brags that he has climbed Mount K2. Billy Brennan exposes him by asking if he made base camp at 25,000 or 30,000 feet. Paul says 30,000 feet, unaware the mountain is 28,251 feet tall.
* In ''Film/LiveFreeOrDieHard'', John [=McClane=] mentions a police code to Thomas Gabriel's mistress, who is pretending to be a police dispatcher. She says that the police had to dispatch all units in regards to the code. [=McClane=] coolly responds, "Dispatch all units for the naked people running around?"
* The main villain of ''Film/TheMasterOfDisguise'' uses this in one of the final scenes to uncover the identity of the disguised hero, who had given himself away by forgetting to change his shoes.
-->'''Devlin:''' Oh, by the way, your wife called.\\
'''disguise!Pistachio:''' Oh. Thanks.\\
'''Devlin:''' You're welcome. ''(turns away, [[DoubleTake then turns back]])'' YOU'RE NOT MARRIED! ''(rips off Pistachio's disguise)''
* Variation in ''Film/MenInBlack'': Agent K exposes an alien posting as a Mexican immigrant by saying insulting and threatening things in Spanish, but in a cheery tone of voice, to see if he reacted appropriately.
* In ''Film/{{Midnight 1939}}'', when Eve poses an an Hungarian royal blood, Georges is onto her and asks if the Budapest subway has been finished yet. She replies that the streets are still torn up. However, as George later reveals, the metro was already finished 50 years ago.
* In the Creator/GeneHackman film ''Film/NarrowMargin'', Hackman's character tells a pair of "RCMP officers" that he might have the guys who've been pursuing him and his witness all over a train "on a 374". They agree, which tips him off to their being fake. 374 is "indecent exposure".
* In ''Film/TheNegotiator'', Chris Sabian is trying to talk down negotiator-turned-hostage-taker Danny Roman. When Roman demands to talk to a confidential informant that can't be located, Sabian reasons that Roman doesn't know the guy either. He substitutes an impostor but is caught when Roman slips in a reference to the impostor's time playing ball for Colorado State and the impostor fails to challenge it despite having Arizona State in his personnel file.
* In ''Film/TheNumbersStation'', after finding out that the station's one-way operator has also been compromised, Emerson confirms it by phoning and getting the code-phrase slightly wrong on purpose.
-->'''Operator:''' Hello?\\
'''Emerson:''' That wasn't the right password.\\
'''Operator:''' What?\\
'''Emerson:''' That wasn't the right password.\\
[''beat'']\\
'''Operator:''' Tell me you killed the girl before you figured that out.\\
[''Emerson hangs up'']
* In ''Film/TheOne'', when Gabe's EvilTwin tries to take his place:
-->'''T.K.:''' That first time we met at the bookstore, did you ever imagine we'd end up in a mess like this?\\
'''Yulaw:''' Even if I had known, I still would have done it.\\
'''T.K.:''' ''(turns gun on Yulaw)'' It wasn't a bookstore.
** [[Series/MysteryScienceTheater3000 Yeah, they won--oh, damn!]]
* Used in ''Film/TheReturnOfThePinkPanther'':
-->'''Clouseau:''' What is your code name?\\
'''Dreyfus:''' I don't have a code name! I never had a code name, lunatic!\\
'''Clouseau:''' I understand sir, but you see, only the real Inspector Dreyfus would know he did not have a code name.
* In ''Film/{{Ronin}}'', [[spoiler:Sean Bean's Spence character is revealed to be a wannabee fraud of a spy when he is asked, by Sam (Creator/RobertDeNiro), what the color of the boathouse at Hereford is (the main British SAS base), and is unable to provide an answer. After a shamed Spence shuffles away, Sam is asked what the color of the boathouse actually is, and he replies, "Hell if I know."]]
* In ''Film/ASeriesOfUnfortunateEvents'', Uncle Monty exposes Count Olaf (pretending to be a herpetologist named Stefano) as an impostor by asking him to milk Petunia the snake. "Stefano" starts looking for udders. [[spoiler:Unfortunately, while Monty realizes Stefano is an imposter, he doesn't realize that he's Count Olaf, which leads to his death.]]
* In ''Film/SonicTheHedgehog2020'', Tom is immediately suspicious when Dr. Robotnik announces that he's from the electrical board, so states that he must know his friend who is also a killer baseball player. Robotnik confirms that he does... and Tom stops him from entering because said friend works for the gas company, and is a frisbee player, also pointing out the electric company usually checks outside the house.
* In ''Film/TheSpiderwickChronicles'' movie, the main character's father seems to appear and he (the kid) asks his dad what it was he wanted to tell him. [[spoiler:He's actually the villain, and the kid finds this out because his father was supposed to tell him they (the parents) were getting a divorce.]]
* ''Film/{{Stalag 17}}'': TheMole tips off suspicious cabinmates by mentioning that he was eating dinner when the attack on Pearl Harbor occurred. While it was noon in the Eastern time zone when the attack happened, it was dinnertime in Germany.
* In the TV movie ''Film/StrandedInSpace'', astronaut Neil Stryker crash lands on a doppelgänger planet that circles the Earth in its orbit, always on the other side of the sun. He is rescued by the people of that planet, who look and sound just like the people of Earth, and placed in a hospital, but the leaders of the planet decide to fool Strykyer into thinking he is on Earth. They are able to monitor his dreams while he sleeps and get information about Earth that way, that they then use to convince him he is on Earth. Stryker becomes skeptical about this after awhile, since although he gets cards and gifts from the people he knows (actually sent by the hospital staff), he never gets to see anybody he knew before the accident. He notices his doctor is named Dr. Revere, so, in order to test him, he asks, "Any relation to Paul Revere?" The doctor carefully answers "no," and then Stryker says, "That's OK. Paul Revere was never much of a ballplayer anyway." Dr. Revere admits he is ignorant about sports figures, but seems to have no idea who Paul Revere was, and this tips Stryker off that he is not in an American hospital, though he only later finds out that he is not even on Earth.
* ''Film/Terminator2JudgmentDay'': The T-800 asks John Connor's foster mother a question about John's dog, but intentionally gives the wrong name to see if she's actually the shapeshifting T-1000, knowing that if is Janelle, she'll give the correct name. "Janelle" doesn't react to his getting the dog's name wrong, thus confirming it's the T-1000. In the extended deleted scene, as the T-1000 leaves the house, it kills the dog and grabs a bloody dog collar, seeing the name on it and realizing that its target knows that it's there and will be avoiding the house.
* In ''Film/ThereWillBeBlood'', Plainview recalls events in his hometown to test whether his half-brother really is who he says he is.

[[folder:Gamebooks]]
* In the third book of the ''Literature/LoneWolf'' series, ''The Caverns of Kalte'', Lone Wolf meets a prisoner in the enemy's fortress, who pretends to be a merchant from [[WretchedHive Ragadorn]], [[spoiler:but is in fact a Helghast shapeshifter sent by the Darklords.]] The game allows asking him a few questions about the city of Ragadorn (visited by Lone Wolf in his earlier quest), [[spoiler:and the monster gets the answers wrong.]] The text never points out whether he is right or not, however: it is up to the player to remember what are the correct answers from the previous book.

[[folder:Literature]]
* In Creator/KirBulychev's ''Literature/AliceGirlFromTheFuture'' series it happens very often, considering that Alice's ArchEnemy is a shapeshifter. In ''[[Literature/AMillionAdventures The Jewelry Box of the Pirate's Mother]]'', Alice encounters someone looking like her friend Rrrr, only she had just helped the latter flee, bandaged and bleeding. Pretending to be happy, she reminds the false Rrrr that she had to come to Brastak (his planet) from Earth via another planet (while in reality she flew straight there from the planet Penelope), tells him that on Earth it's raining mushrooms, and asks him if he remembers how they met on Pataliputra and played in the snow (that planet has tropical climate even in the polar regions). When he doesn't react to any of it, she is left with no doubt that it's an impostor. Subverted, since she gets carried away so much with thinking up absurdities, the impostor also realizes she doesn't believe him.
* ''Literature/{{Animorphs}}'':
** When David morphs into Marco, Rachel taunts the real Marco with "You know you're a toad, right?" and Cassie asks him to describe how it felt when they morphed trout. They know it's Marco because he answers [[DeadpanSnarker sarcastically]] ("Kiss me and I'll become a prince," and "The cracker crumb coating chafed," respectively).
** In another book, a Controller says the word "Andalite!" loudly to a person he suspects to be an "Andalite bandit" in human morph. In reality, he's as close to being right as you can be, as the person in question is Cassie in Rachel morph. But he's satisfied when, without missing a beat, Cassie/Rachel immediately replies as if he had just said the words "and a light".
** Marco also does this after his dad discovers Z-space, trying to see if his dad's a controller by pointing out that the trip his dad wants to take would mean they'd be gone more than three days, the amount of time a Yeerk can go between feedings.
* ''Literature/TheCurseWorkers'': In ''White Cat'', Cassel casually asks his brother Barron if he remembers certain incidents from their childhood, and Barron says he does... except the incidents are things Cassel made up, or that happened to someone else. In this case, though, Barron isn't an impostor; he's [[spoiler:suffering from memory loss]] and trying to cover it up because [[spoiler:he's a memory worker suffering the magical backlash from repeatedly altering Cassel's memories.]]
* ''Literature/DirkPittAdventures'': In ''Iceberg'', hero Dirk Pitt meets scientist/businesswoman Kristi Fyrie at a dinner. From the start, Pitt thinks something is off as Kristi talks of having spent years in the South American jungles but Pitt [[SpotTheImposter notes her skin is nowhere tan enough for that.]] He talks of wanting a steak that's basically an echidna seaweed and she agrees it's a delicious dish in New Guinea. Later in the book, Pitt explains it to an ally who doesn't grasp it at first.
-->'''Pitt''': How would you react if I said I just barbecued a New York cut steak wrapped in porcupine quills?\\
'''Ally''': I'd say something.\\
'''Pitt''': You get the idea.
** A slight subversion in that it turns out [[spoiler: Pitt believed Kristi was an imposter posing as the sister of the late Krisjan Frye; in reality, she ''is'' Frye having secretly undergone a sex change.]]
* ''Literature/{{Discworld}}'':
** ''Literature/CarpeJugulum'': A vampire tries to get Magrat to open a door by pretending to be Nanny Ogg. Magrat demands that "Nanny" first tell [[NoodleIncident the joke about the old woman, the priest, and the rhinoceros]]. The vampire tries to protest that this isn't the time for that -- proving it's an impostor, since the ''real'' Nanny Ogg [[DirtyOldWoman always has time for a dirty joke]]. It's not pointed out, but longtime readers might also catch the fact that the vampire had exclaimed "lawks!", a stereotypical old-lady cry which the elder witches only resort to when they're ''pretending'' to be harmless.
** ''Literature/FeetOfClay'': Dorfl the golem comes into the Watch building partway through the book and confesses to committing the crime they had been investigating. Carrot, suspecting (correctly) that Dorfl is turning himself in to protect the real criminal, tests him by including incorrect details:
-->'''Carrot:''' You killed the priest as well?\\
'''Dorfl:''' Yes.\\
'''Carrot:''' You beat him to death with an iron bar?[[labelnote:*]]He was actually bludgeoned with a museum artefact[[/labelnote]]\\
'''Dorfl:''' Yes.
** The Klatchians in ''Literature/{{Jingo}}'' don't know ''exactly'' what Sgt. Colon is up to (they think he's a spy from somewhere else doing a really bad impersonation of an Ankh-Morpork spy) but they do know that he [[TheDitz can get out of his depth on a wet pavement]], so they tell him the Klatchian army has gone to "En al Sams la Laisa," [[FunWithForeignLanguages which translates to The Place Where the Sun Shineth Not.]] Vetinari is unimpressed when Colon reports this.
* In Creator/RobertAHeinlein's ''Literature/DoubleStar'', a disguised actor impersonating a politician meets with the Emperor of the Solar System. The Emperor insists that he play with his toy trains, which the actor dutifully does. The Emperor then asks him who he ''really'' is, because all the past times he had met with the politician and asked him to play with the trains the politician had refused and teased him about having such a childish hobby -- it was a sort of game between them. It was an interesting play on this trope, as the actor's impersonation was so flawless that the Emperor hadn't really been all that suspicious until that point.
* In Creator/AaronAllston's ''Literature/GalateaIn2D'', when Roger suspects the false Donna, he asks if Elsie's at David's, rather than Dylan's.
* ''Literature/HarryPotter''
** In ''[[Literature/HarryPotterAndTheHalfBloodPrince Half-Blood Prince]]''
*** The Ministry advises people to ask this kind of question to make sure a Death Eater isn't impersonating your friend. Harry quickly figures out for himself that when magical compulsion is one of the favorite tools of the bad guys, this sort of thing is the barest of bare-bones contingencies. Dumbledore states he that agrees with him.
*** Arthur Weasley comes home from the Ministry and passes Molly's challenge at the door. When she goes to open it, he grabs it and pulls the door shut again so he can challenge her. Afterwards, Molly comments that it's silly, since anyone impersonating Arthur could easily torture the question and response out of him. He agrees with her, but says that they should do it to set an example.
** In ''[[Literature/HarryPotterAndTheDeathlyHallows Deathly Hallows]]'', members of the Order of the Phoenix start doing this to each other. There is the slight variant that they don't agree on what questions to ask beforehand, instead just asking about random moments in their past, making the system more secure.
* ''Literature/HardyBoys'': In the Super Mystery "Stage Fright" the brothers are on the receiving end of this from a suspicious theater employee.
-->'''Damien:''' So what shows have you done?\\
'''Joe:''' Uhh. ''Theatre/ByeByeBirdie''. ''Theatre/TheMusicMan'', you know, the usual.\\
'''Damien:''' So you guys are big [[Creator/StephenSondheim Sondheim]] fans? Me too.\\
'''Joe:''' We love him. Now if you don't mind, I have to-\\
'''Damien:''' That's funny. Because none of those shows are by Sondheim.
* In Kurt Steel's ''The Imposter'', the president of an aircraft company, after discovering the dead body of a double who was sent to impersonate him in a Nazi plot but ran afoul of an entirely ''separate'' Nazi plot to assassinate said president, decided to pretend to be the double in an attempt to flush out both sets of enemy agents, but was revealed when one of the dead man's more suspicious associates made some comments about things which had never happened.
* Appears in ''The Light Bearer'', a historical-fiction story about the Roman conquest of Germania. Germanic chief Baldemar reveals an imposter to be a foreign spy by asking him if a famous local woman has recovered from an illness, to which he replies that she has -- she actually died the previous year.
* Creator/IsaacAsimov's "Literature/LittleLostRobot": When one of the NS-2 robots with a modified version of [[ThreeLawsCompliant the Three Laws]] tries to hide in a [[NeedleInAStackOfNeedles group of physically identical NS-2 robots]] with unmodified Three Laws, it has to convincingly act as if it were an unmodified NS-2 robot. Dr Calvin designs three tests to flush out the imposter robot:
** The lost robot foils the first test because, while it doesn't have to rescue a human in danger, it [[RobotsThinkFaster can choose to do so as quickly as the other robots are compelled to by the First Law]].
** Dr Calvin puts the robots in a situation where trying to rescue a human would (as far as they know) destroy them (prohibited by the Third Law unless trumped by the First or Second). Indeed, the lost robot does not try to rescue the human — but has cleverly convinced the other robots not to try either (that they'd be destroyed before succeeding becomes an argument to [[MurderByInaction ignore the First Law]]).
** In the third attempt, Dr Calvin puts the robots in the first situation again — but the unmodified robots think it's the second, and stay still; the lost robot had been recently trained to recognize the difference between certain radiation wavelengths while the unmodified robots hadn't.
* Also shows up in ''Literature/TheLostWorld1912'', when [[IntrepidReporter Malone]] is trying to gain [[BadassBookworm Professor Challenger's]] trust by pretending to be a fellow scientist, Challenger quizzes him on various scientific terms, all of which Malone claims to be familiar with. Challenger then informs him that he had been speaking gibberish and tackles him out the door.
* In Lawrence Block's ''Me Tanner, You Jane'' Evan, after spending several days with a man claiming to be fellow agent Sam Bowman (whom Evan had never met), becomes suspicious and states in casual conversation that the chief of their agency is a by-the-book fellow who wears a plaid hat. "Bowman" doesn't contradict either "fact".
* In ''[[Literature/MichaelVey Rise of the Elgen]]'', Hatch brings [[EvilTwin Tara]] to visit Michael's captive mother with him, claiming she's Michael's friend Taylor and having her praise the Elgen. Mrs. Vey bluffs Tara by asking about a watch Taylor gave Michael (which was actually a gift from his mother) and casually saying that her dad is a schoolteacher. Tara fails to catch either mistake, giving herself away.
* In a ''Literature/NancyDrew'' book, Nancy has become suspicious of a young man claiming to be the long-lost son of the wealthiest man in town. (The man was presumed dead in an avalanche during a trip to Switzerland but has returned several years later, claiming to have been recuperating in a hospital all this time). While initially charming everyone, he still makes several mistakes -- buying his housekeeper a chocolate cake for her birthday when he should know that she's allergic, as she once had a severe reaction in front of him. Nancy finally trips him up by gushing about his 18th birthday party (the last one he had before vanishing), mentioning how cool his "giant purple and white football cake" was. The man enthusiastically agrees -- until Nancy coldly informs that that's NOT the kind of cake that was served.
** Nancy also does this to Beth's boyfriend Alan in one of the ''Case Files'' stories when Beth goes missing, and she suspects Alan knows more than he's letting on. She asks if Beth took a specific type of medication. When Alan says yes, Nancy realises he's bullshitting because Beth is allergic to said medication, and taking it could kill her. Alan is forced to come clean.
* In John Barnes's ''Literature/OneForTheMorningGlory'', the Duke challenges Sir John to name Calliope's birthmark on her thigh. Sir John sputters. Given that with Sir John's reputation, any imposter would have improvised because of course Sir John would have known.
* ''Literature/TheOtherworld'': In ''Haunted'', Lucas asks "Jaime" if she wants Indian food, confirming Eve's claim that she's been possessed by a demon ghost.
* This is how, in an early arc of ''Literature/PerryRhodan'', Atlan discovers that the eponymous protagonist has been replaced by a doppleganger [[spoiler:-- specifically, his first son who has undergone a FaceHeelTurn]]. The impostor has most of the original's current knowledge due to his allies [[MindProbe telepathically interrogating]] the former before setting the plot into motion, but Rhodan managed to slip in just enough misinformation about his initial clashes with Atlan for the latter to catch on once the subject comes up. (In their first duel in that museum on Venus, they fought with broadswords, ''not'' smallswords, and the imposter then failing to recognize a silly little rhyme that had special meaning for them both after a long, wearying chase on the planet [[MeaningfulName Hellgate]] cinched it.)
* In one of Robert Asprin's ''Literature/PhulesCompany'' novels, a Space Legion soldier trying to prove his identity is asked "Who led the Galactic League in free flies last season?" Not only can he not come up with the player's name, he misidentifies the sport--and his comrades conclude that it's really him, because he's known to be completely ignorant about sports.
* In Creator/KerryGreenwood's "Raisins and Almonds", Phryne Fisher discovers that a man who has gone to great lengths to masquerade as a Jew is not actually Jewish by the fact that he cannot sing the lullaby "Rozhinkes mit Mandlen" ("Raisins and Almonds"). However, this would not have worked in real life. The lullaby is written in Yiddish, a language based on Middle High German spoken by central and Eastern European Jews. The group of Jews involved in the story were from a community where their Judaic language would have been Ladino, an entirely different language based on Spanish.
* In one of the ''Literature/RangersApprentice'' books, Will is in disguise as a minstrel. The lord of the castle he's visiting asks if his instrument was made by the master luthier Gilperon, and Will says no. Later the lord informs him that the luthier's name is actually Gilet, which a real musician would have known.
* ''Literature/TheReynardCycle'': Reynard enters into one of these with a [[{{Shapeshifting}} shapeshifter]] who has done its research during ''Reynard the Fox.'' The one thing it fails to mimic is [[spoiler: Reynard's complete contempt for authority, even in the face of death.]]
* ''Literature/RhythmOfWar'' (fourth book of ''Literature/TheStormlightArchive''): Shallan suspects that one of her Lightweaver apprentices is secretly a spy for the Ghostbloods, but isn't sure which of them to suspect. So while conversing with the suspects, she mentions that she's seen a corrupted spren (telling each of them that it was a different species of spren) and asks them to keep it a secret for now. Sure enough, during her own negotiations with Mraize, he mentions the corrupted spren. [[spoiler:As it turns out, the spy was actually reporting to someone entirely different, a friend who was worried about Shallan. They were unaware that Mraize could listen in on those conversations]].
* In ''The Savage Damsel and the Dwarf'', the title characters are staying with a group of [[KnightInShiningArmor knights]], and the dwarf mentions that he used to serve Sir Gaheris. One of the knights asks casually if Sir Gaheris is still as skilled a swordsman as ever. The dwarf [[spoiler:who is actually Sir Gaheris under an enchantress' curse]] passes the test when he responds that the knight must be thinking of someone else, since Sir Gaheris is a notoriously abysmal swordsman.
* It also shows up in Creator/ArthurConanDoyle's Literature/SherlockHolmes story ''The Adventure of the Three Garridebs''. When a man claiming to be an American lawyer recently arrived in London calls on Holmes, Sherlock first asks whether the American had placed an ad in the "agony columns" and is assured that he did, then when the 'American' says he's from Kansas, Holmes mentions an old correspondent of his, Dr Lysander Starr, who was "mayor of Topeka in 1890." The 'American' assures him that Dr Starr's memory is still honored in Kansas. After he's left, Holmes assures Watson that he's not what he claims - there was no ad in the agony columns and "Dr Lysander Starr" is completely fictional.
* In the fourth book of ''Literature/ASongOfIceAndFire'', ''Literature/AFeastForCrows'', Sam Tarly arrives at the city port of Oldtown where he hears from an Oldtown harbour offical that the Ironborn attacking the coastline of the Reach seized a Tyroshi ship, killed its crew, then [[KaleidoscopeHair dyed their hair all different colours]] in the fashion of Tyrosh, hoping to slip into Oldtown in disguise and then cause chaos to allow an attack on the city. Unfortunately, the captain of one of the ships in Oldtown's harbour was married to a Tyroshi woman, and when none of the "Tyroshi" crewman answered him when he hailed them in their native language, the captain realised something was wrong and raised the alarm.
* In the ''Literature/TomSwift'' book ''Monster Machine'' in the aftermath of the main cast being kidnapped Tom and Rick are trying to rescue their girlfriends from a room when a computer sensor tells them it's filled with poison gas. They ask the girls to answer specific (trick) questions which they are unable to do. A little later, when they find the real girls (wearing gas masks) they ask the same questions just to make sure and this time they know the right answers.
-->'''Tom:''' Mandy, tell me what color bathing suit you wore on our date last Friday.\\
'''Mandy:''' Tom, what are you talking about? Nobody wears a bathing suit to the movies, not even in California!
* In Creator/VladimirVasilyev's ''The Treasure of the Kapitana'', an [[IstanbulNotConstantinople Albionian]] (British) captain is seeking to hire a Tauridan (Crimean) pilot to help him sail the treacherous waters of the Euxine (Black) Sea. While the local pilots (called "shtarkhs") use more magic than learning to navigate the sea, Ralph also has a piloting degree from the Southampton Naval Academy. He shows his diploma to the captain, who immediately asks how his good friend the chancellor of the academy is doing, seemingly forgetting his name. Ralph helpfully supplies the name and, when the captain asks how the chancellor's wooden leg is feeling, calmly corrects him that, when Ralph last saw the chancellor, he had two good legs but only one eye.
* ''TabletopGame/Warhammer40000'': Used in Creator/DanAbnett's third Literature/{{Eisenhorn}} book, ''Hereticus''. Eisenhorn spots an imposter posing as a trusted member of his retinue by saying their situation reminded him of the tight spot they'd been in fighting Beldame Sadia on Eechan. The imposter agrees, alerting Eisenhorn (and any particularly astute readers) to the trick -- they'd actually fought Sadia on Lethe Eleven.
* In ''Literature/{{Worm}}'', the fact of [[spoiler:Regent's PeoplePuppets power]] leads to [[spoiler:Weld subjecting Shadow Stalker]] to one when she shows up with several members of [[spoiler:the Undersiders]] in custody.

* A short-lived spy series in the sixties had the hero pull a DeadPersonImpersonation of a wealthy man who'd been killed by Soviets when they [[IdenticalStranger mistook him for the spy]]. The rich man's wife caught on to the imposture fairly quickly, because her husband was a {{Jerkass}}, and the agent treated her with courtesy. She tested him by asking if he'd consulted his sister about a certain business dealing. Not having had the chance for a proper briefing about the man he posed as, he said dismissively, "What does she have to do with it?" Of course, "My husband doesn't have a sister." She wound up covering for him anyway.
* ''Series/AgentsOfSHIELD'':
** In "Face My Enemy", Agent 33 disguises herself as agent May to lure Coulson into a trap. When Coulson gets suspicious, he casually asks 'May' if they could finally get that cup of coffee they discussed years earlier when this mission is over. When May agrees, Coulson knows enough; the real May hates coffee.
** In "Love in the Time of HYDRA" this happens again, this time Agent 33 vs Talbot. To be fair, Talbot realizes very quickly and notifies Coulson "The nanomask is in play", and assembles all female staff workers, even telling his security not to let anyone disturb him, even if it is him. He even knows a lot about his staff, knowing which lines to say and how they should respond. However, he fails to realize that 33 can adopt either gender; or believed they were restricted to one gender, as when he himself was impersonated, it was by a man whom he knows is in custody.
** In "Code Yellow", Deke bluffs Sarge (who is posing as Coulson) by asking about "Agent Doug". None the wiser, Sarge keeps it circumspect: "Doug's Doug".
* ''Series/{{Alias}}'': It seemed to happen quite a lot, due to all the spies, moles, and infiltrators, but mostly due to Project Helix, an AppliedPhlebotinum that allowed one person to be identical to another. Will Tippin held a gun on Sydney Bristow because he thought her to be an impostor. He asked her what he spilled on his shirt a decade ago before a job interview [[spoiler: and she ''knew'']]. Similarly, Sydney realized Francine had been killed and replaced with a gene-disguised impostor when she accepted a bite of coffee ice cream, which Francine hated.
* ''Series/{{Batwoman}}'':
** Kate's father, Jacob, seems to have quickly forgiven her stepmother, Catherine, for a major betrayal. This is out of character enough to make Kate suspicious, so she calls Jacob on the phone and reminisces about the snowstorm on the day he married Catherine. The impostor doesn't know that the wedding was on a hot summer day.
** Tommy Elliot (aka "Hush") uses the same technique to look like Bruce Wayne. Already suspicious of "Bruce" acting odd, Julia asks if Bruce just came from seeing her father, Alfred, at his lake house in Glasgow. When Bruce confirms it, Julia knows he's a fake as her father lives in a flat in London.
* One episode of ''Series/BigWolfOnCampus'' uses this trope to help the two main protagonists distinguish between who is or isn't possessed by a vengeful ghost out to murder the main hero. When sidekick [[PerkyGoth Merton Dingle]] is possessed, [[WolfMan Tommy Dawkins]] is able to figure it out after Possessed-Merton fails to remember the secret word that lets them know if he's possessed or not.
* Averted on ''Series/TheBlacklist'' as Liz is undercover as an arms dealer from Harvard at an illegal auction. One of the leaders is suspicious and asks her about "the Duckie". Liz bides time by faking a sneeze. Luckily, Red is nearby and covers by complaining about "the Duckie" being the train that took drunken Harvard grads about. He then acts like he and the woman Liz is impersonating go back a long way to solidify her cover.
* ''Series/BurnNotice'':
** Michael, in one of his many voiceovers, mentions that the risk of falling prey to one of these is the reason why spies avoid assuming other people's identities whenever possible... and that, if you do have to do it, it helps if the other person is scared to death of the one you're pretending to be.
** A completely different episode has him as the bluffer instead of the imposter, noting in his voice-over that if someone is asking for information, it's basic security to do this to ensure they're who they say they are and it's a pretty good tactic:
--->'''Michael:''' Gustavo, we talked about this on the phone. I'm giving you eight thousand dollars for a file. Part of what that money buys is privacy.\\
'''Contact:''' (''with accent'') I don't care what I said on the phone. You don't tell me what I want to know, you don't get this file. Eight thousand, no eight thousand.\\
'''Michael:''' The deal I made with Gustavo was for ''ten'' thousand dollars, not eight thousand dollars. He was very clear about that number. And we never talked on the phone. You wanna tell me who you are?\\
'''Contact:''' (''smiles and drops the accent'') I can explain. (''pulls a knife on Michael'')
* ''Series/CharliesAngels'':
** In the pilot for the original series, Kelly Garrett (Jaclyn Smith) was masquerading as a long-lost heiress. She met up with Aram Kolegian (Creator/TommyLeeJones), who had known the heiress before her disappearance. He casually mentioned several things to her about their past which she agreed with. After she left, he said to himself that he didn't know who she was, but she sure wasn't the heiress because the things he had said were lies.
** Subverted earlier in the episode, when an old friend of the family tries to bluff Kelly with stories of her (well, the girl she's pretending to be) childhood littered with incorrect details. Kelly, however, corrects each mistake and calls him out on what he's doing rather quickly.
* On ''Series/Charmed2018'', Michaela is at first happy her adoptive mother has dropped by for a visit but suspicious of her behavior. They have a talk as Michaela says "I'll always be your little Baa-Baa-Boo" and her mother embraces as if it's an old childhood nickname. Too bad for her Michaela made the entire thing up on the spot so knows this is an imposter.
* On ''Series/ChillingAdventuresOfSabrina'', Ambrose is being held prisoner and falsely accused of murder by some nasty witches. Hilda comes to see him and is met by a calm Ambrose who talks of how he deserves what's happening to him and Hilda can't help. Meanwhile, the real Ambrose is being met by a witch using a glamour to pretend to be Hilda and press Ambrose to confess to save the family. Each of them is able to see something is wrong and test it. First, Hilda talks of a party they had last year for the death of Zelda’s Familiar Vinegar Tom, Ambrose agreeing it was great... and Hilda stating that Vinegar Tom died in 1989. For his part, Ambrose says he'll be happy to confess... as soon as "Hilda" tells him what her favorite episode of ''Series/FawltyTowers'' (a show she's never watched) [[note]] Hilda Hates Fawlty Towers.[[/note]] is. Both impostors realize they've been found out.
* Played much less seriously in the pilot of ''Series/TheChicagoCode''. Wysocki asks his partner what time the game starts, and Evers tells him 1:20. Wysocki notes that the White Sox have the day off, which blows Evers' cover revealing himself for the traitorous Cubs fan he truly is.
* On ''Series/DesignatedSurvivor'', Hannah is investigating a brewery outside of Boston with the owner talking of having grown up in the area and brushes off knowing of anything with a genetic company. Hannah says he should get "Gronk" to promote his beer, the man blinking in confusion before she clarifies she meant New England Patriots star Rob Gronkowski. As Hannah tells her British partner, there's no way someone who grew up in this area could ''not'' be a die-hard Patriots fan.
* ''Series/DoctorWho'':
** In the eponymous final episode of [[Recap/DoctorWhoS1E5TheKeysOfMarinus "The Keys of Marinus"]], Ian Chesterton notices that "Arbitan" (actually Yartek, the leader of the Voord, who killed him at the end of the first episode of the serial) is behaving very suspiciously, including not seeming to recognize Altos, who he sent to retrieve the keys before the Doctor and Companions, so he gives him a fake micro-key that they also acquired on their travels instead of the real one — the real Arbitan created the keys and would be able to spot the slight flaw that distinguishes it from the real ones, but an impostor wouldn't know the difference.
** In [[Recap/DoctorWhoS13E4TheAndroidInvasion "The Android Invasion"]], the Doctor realizes he's dealing with a Sarah Jane android when she accepts some ginger beer, the real Sarah Jane having told him earlier that she can't stand the stuff.
** In [[Recap/DoctorWhoS21E6TheCavesofAndrozani "The Caves of Androzani"]], General Chellak is running a war against Sharez Jek and his army of highly lifelike androids. One android happens to be impersonating a subordinate officer, Major Salateen, which is passing intelligence on to Jek. Chellak only gets wise when the real Salateen, who had been abducted by Jek, turns up out of the blue. Rather than report the security breach and suffer the consequences, Chellak takes Salateen's suggestion to feed disinformation to the android.
*** but foiled when the android Salateen detects the presence of the real Salateen, allowing Jek to counter-bluff and sabotage Chellak's assault on his lair.
** Martha uses this on her roommate Jenny in [[Recap/DoctorWhoS29E8HumanNature "Human Nature"]]. As it turns out, Jenny has been possessed by an alien lifeform; the alien's responses to Martha's conversation confirm that not only is she not really Jenny, she's not really human.
--->'''Martha:''' Would you like some tea?\\
'''Jenny:''' Yes, thanks.\\
'''Martha:''' I could put a nice bit of gravy in the pot. And some mutton. Or sardines and jam, how about that?\\
'''Jenny:''' I like the sound of that.\\
'''Martha:''' Right. Hold on a tick. ''[discreetly flees]''
** [[Recap/DoctorWhoS30E4TheSontaranStratagem "The Sontaran Stratagem"]]/[[Recap/DoctorWhoS30E5ThePoisonSky "The Poison Sky"]]: The Doctor uses this on the clone who has replaced [[spoiler:Martha]] by doing things like saying "Avanti" instead of [[CatchPhrase "Allons-y!"]] and asking her if she's called her family to warn them about the poisonous gas. Subverted since the Doctor knew from the start that this was a Sontaran clone and was using her to his advantage.
* ''Series/FamilyMatters'': Urkel is the captive of a man impersonating Carl's partner. Carl hears him talking through the door and not giving the standard reply of, "Not if I see you first," when he says, "See you later." Carl baits the kidnapper by sliding money under the door that he doesn't owe him and breaks it down when he comes to get it, then apprehends the felon.
* The GrandFinale movie for ''Series/TheFamousJettJackson'' has the titular character swap places with his secret agent ShowWithinAShow character Silverstone. At the time, the show ''Silverstone'' was dealing with a new BigBad (Creator/MichaelIronside) with the ability to [[VoluntaryShapeshifting disguise himself as any person]], and Jett (the actor) has to figure out a way to defeat him. Suspecting that the BigBad has infiltrated the spy agency, Jett demands Silverstone's mentor sing him the song he sang Silverstone as a baby. While the mentor sings "The Itsy Bitsy Spider", Silverstone's partner starts slowly moving towards the dimensional key. Jett catches her hand and has the mentor invoke this trope. The question is about the name of the plant he gave her for her birthday. She replies that she doesn't have one for it. Of course, there is no plant, and she is the BigBad in disguise.
* In an episode of ''Series/{{Farscape}}'' where Crichton believes he has returned to Earth, the alien masquerading as [[spoiler:his father]] pulls one of these. In a later episode, [[spoiler:when Crichton really ''has'' returned to Earth and meets his father]], Crichton references that conversation.
* In an episode of ''Series/TheFlash2014'', Cisco and Caitlin try to bluff Laurel's Earth-2 double Black Siren by pretending to be their own {{Evil Doppelganger}}s Reverb and Killer Frost, respectively. It seems to work at first, then Black Siren tosses a random object to "Reverb". Cisco catches it, only for Black Siren to reveal that all doppelgangers from Earth-2 have a different dominant hand. It's also possible that [[spoiler:she's aware that the real Reverb and Killer Frost have been killed by Zoom]]. This ends up being forgotten in future episodes, as the presence of multiple parallel Earths makes that nonsensical.
* Subverted on ''Series/FirstWave''. Cade is met by someone who looks like the uncle who raised him but is suspicious he's a Gua imposter. He talks of his uncle helping Cade cope after her was cut from the school hockey team and without missing a beat, the man laughs "what are you talking about, you won them the championship!" As it later turns out, Cade was ProperlyParanoid as this is a well-informed imposter.
* ''Series/{{Frasier}}''. Roz discovers she's pregnant, and Frasier encourages her to find the father and tell him the news. She claims one morning at Café Nervosa that the father was an architect, and not much else. Later, at Frasier's apartment, she mentions that he was an ''archaeologist'', and Frasier gets her into the kitchen to pull one of these off the bat by asking her how the two met again.
-->'''Frasier:''' This morning, you said you met him on a double date.\\
'''Roz:''' Oh yeah, it ''was'' on a double date! \\
'''Frasier:''' '''''THIS MORNING YOU SAID NOTHING!'''''
** After Daphne finds out that a patient of Niles' has a crush on him, she and Roz go to her office to find out what she looks like. When they meet the woman, Roz rants about how they "flew in from corporate for a meeting", only to have the woman bluntly ask, "How could you fly in from corporate? Corporate's downstairs."
* On ''Series/{{Fringe}}'', Peter eventually uses this on [[spoiler:Fauxlivia]], reciting a line of Greek to her that the genuine article would have recognized. Unfortunately he wasn't very subtle about it, and she was waiting in the next room with a gun.
* ''Series/{{FullHouse}}'', subverted in the last episode of Season 8 since used to check the character's wellbeing rather than uncovering an impostor: Michelle falls from a horse and gets amnesia for a week (trying to play along as if recognising everyone normally) but then gets her memory back. Unlike other relatives, Danny and Joey both asked her trick questions — what day does Danny always vacuum the stairs and what's the capital of Nevada? Michelle correctly answers that stairs are vacuumed every day but doesn't know the capital — just as always. Her memory's back!
* ''Series/GameOfThrones'': Brienne is on a secret mission to exchange the captured Jaime Lannister back to his family in exchange for both of Catelyn Stark's daughters. Along the way they run into some Stark soldiers, and one of them recognizes Jaime. Brienne tries to claim Jaime is a common thief she caught and is bringing to justice, but the leader of the soldiers upends the ruse by demanding [[StereoFibbing they both say his name at the same time]]. Naturally the two hadn't bothered to think of an alias ahead of time, so Brienne has to fight her way out of it.
* ''The Gemini Man'': Used by Intersect Agent Sam Casey (also seen in the ''Series/MysteryScienceTheater3000'' episode "Riding With Death", featuring two episodes of the series repackaged as a TV-movie) on Dr. Hale, who is supposed to be in the trailer of the truck Sam is driving, but suspected of being in the helicopter that's been following the truck the entire episode (which he is). Dr. Hale has rewired the intercom in the back of the truck to communicate with a radio unit in the helicopter.
-->'''Sam Casey:''' Sorry about that last bump, Dr. Hale. I hit a hole in the road.\\
'''Crow:''' He's mellow but cunning.\\
'''Abbey:''' ''(trapped in the back of the truck)'' What bump?\\
'''Sam:''' I hope it didn't jar you too badly.\\
'''Dr. Hale:''' Uh, well it almost knocked my glasses off, but that isn't important. We have to make up that lost time.
* A ''Series/GeneralHospital'' storyline had a woman named Katherine Crawford coming to town, claiming to be friends with the recently deceased Dominique Baldwin and rapidly befriending her widowed husband, Scott after learning that Dominique was dead. However, Scott's friend Lucy was immediately suspicious and began to investigate. Her first discovery, that no one named Charles Crawford had died recently (Katherine was claiming to have been recently widowed herself) was thwarted when Katherine stated that her married name had been ''Reynolds''. But her second attempt proved successful when she was able to present the ''real'' Katherine Crawford to Scott. Unfortunately, Scott decided to believe Katherine's lame excuses, leading Lucy to have to make ''another'' discovery to prove Katherine's duplicity--upon re-reading the letter than Katherine wrote to Dominique, she realizes that Katherine used her fake name, something that would have been unnecessary if Dominique knew her. Which meant that Katherine ALREADY knew that Dominique was dead before coming to town, and that her intent from day one was to scam Scott out of the money that he'd inherited.
** From the same show: Twice, SerialKiller Ryan Chamberlain escaped from prison and took his twin brother's place in Port Charles society so that he could continue to stalk Felicia Jones, who he was obsessed with. In both cases, Kevin managed to alert people by discussing events that Ryan couldn't have known about.
* A case of bluff the witness is used in ''Series/TheGoodWife'' episode "Unprepared". [[spoiler: Once they realize the witness is the one who committed the crime (he claimed he made a cell phone call in an area with a phone block), they ask if he made the call during the intermission of the recital he was at. He says he did, and they point out that there was no intermission.]]
* ''Series/{{Heroes}}'': When Peter is controlling the body of Jesse, one of the Level 5 villains, Knox, his fellow escapee, catches him this way by asking "Jesse" if he can't wait to see his family and friends in Detroit, when Jesse's family is from Vegas and he doesn't have any friends.
* ''Series/HogansHeroes''
** The crew is trying to decide if their most recent addition is truly a POW or a spy. Hogan tells his men not to ask about Ty Cobb's batting average as that's the first thing a spy would learn. Later on, after correctly answering questions on American cities, Carter asks the spy if he knows anything about Ty Cobb, to which the spy asks "Want to know his batting average?"
** In another episode, one of Hogan's crew is trying to infiltrate a meeting of German officers under guise of another visiting officer. One of them, perhaps sensing an impostor, says he had heard that he injured his hand in a hunting accident, and asks him which hand it was: the right or the left? The spy manages to dodge the question by saying: "Thanks to superior German medical techniques, you can't tell which of my hands was injured!"
** In the pilot episode, Hogan and his men test incoming escaping [=POWs=] this way first by asking what unit they're supposedly from, then feeding them some fictitious names while asking how Hogan's "old buddies" in the unit are doing. Carter passes handily, while a German infiltrator is later tripped up by replying that "Major Campbell" is doing fine.
* ''Series/KamenRiderBlade'' had a variation on this in the Hyper Battle Video, where a [[KillerRobot Trial]] has impersonated [[TheHero Kazuma]], and subsequently Blade. [[TheLancer Hajime]] roots out the Trial by calling out Kazuma's name; after the battle, he explains that the Trial reacted first because of its superhuman reflexes, to which Kazuma responds "That makes me sound kind of slow, doesn't it?"
* ''Series/KnightRider''
** Michael Knight finds that the villain with LatexPerfection is not Devon by calling him Ishmael, which confuses him. Earlier in the episode, Devon had greeted Knight quoting the beginning of ''Moby-Dick'': "Call me Ishmael".
** In another episode, when a girlfriend expresses concern about her father's behavior (he's been kidnapped and replaced with an impostor), Michael chats with him about the Disneyland tickets he had supposedly asked him for. When the man responds enthusiatically, Michael and the girl know he's a fake -- they had never made any such plans.
* In an episode of ''Series/LieToMe'', Cal and Torres visit a fertility clinic, posing as a married couple looking for an egg donor. Cal asks if what they've been told is possible, namely that his "wife's" infertility is due to an estrogen imbalance caused by the Coriolis effect, and the doctor agrees that it's a definite possibility. Had he been a real doctor, he would have known that [[http://en.wikipedia.org/wiki/Coriolis_effect the Coriolis effect]] has nothing to do with medicine.
* In a ''Series/LawAndOrderSpecialVictimsUnit'' episode, when a man claims to have been watching a ball game as an alibi, Stabler starts chatting about how lousy the game was, only for the confused man to tell him that the game went ''well'', thus confirming that he's telling the truth.
* Averted in season 5 of ''Series/{{Lost}}'' when Pierre Chang realises that Hurley is probably from the future. Hurley blows his cover when he mistakes a straight question for a bluff.
-->'''Chang:''' What year were you born?\\
'''Hurley:''' 1930.\\
'''Chang:''' So you're 47 years old?\\
'''Hurley:''' Yeah.\\
'''Chang:''' And you fought in the Korean war?\\
'''Hurley:''' There's no such thing!
* On ''Series/MagnumPI2018'', Magnum is sent on a secret mission with a pair of CIA operatives. From the start, he senses something is off and talks to one agent on a "Neil Diamond fiasco, you must have read my file on it" and the man says he did and hopes this isn't a repeat. Magnum then talks to the nervous tech guy on how he trained at Hammond Air Force base and a diner with bad food nearby. When the two try to pull a double-cross, Magnum relates he was onto them from the start as there was no "Neil Diamond" mission and that diner doesn't exist.
* In ''Series/{{Merlin|2008}}'', Arthur does this to goblin-possessed Gaius. Arthur offhandedly mentions Merlin's upcoming execution; when "Gaius" is completely nonplussed, Arthur immediately knows something is wrong.
* ''Series/TheMiddleman'': The Middleman is being possessed by an evil genius. Ida, warned by Wendy, innocently asks if there's anything he needs from her before she goes home to her husband and children. The fake Middleman, not knowing that Ida is an android, doesn't suspect a thing.
* In one episode of ''Series/{{Misfits}}'', Jess exposes an impostor by casually asking the character in question about the new car he doesn't have.
* ''Series/{{Monk}}'':
** In "Mr. Monk and the Airplane," Stefan Chabrol has had his wife killed and replaced with his mistress. Unfortunately, a family friend of Barbara's happens to be on the plane with them, and figures out she's not who she supposedly is.
** In "Mr. Monk Visits a farm" Monk goes undercover as a Mexican worker at the farm of murder suspect Jimmy Belmont. Belmont quickly becomes suspicious of Monk, approaches him and asks him a question in Spanish (which Monk isn't that fluent in). Monk just replies ''"Si, si"'' to Belmont's test question.
--> '''Jimmy Belmont:''' I just asked if you got a squirrel in your pants.
* ''Series/MurderSheWrote''
** In an episode, Jessica becomes suspicious of a man's claim of having been in the armed forces. To that end, Jessica asks if he served in X division with her husband Tom. The man readily claims that he did and describes Tom as a fine soldier and one that he admired and respected. Of course, Jessica knows he's lying as her husband's name was NOT Tom, and he served in a different division of the armed forces than the one she named. However, she doesn't confront him with this, nor reveal it to anyone else, knowing the man could easily HandWave it as an honest mistake rather than an outright lie.
** In another episode, she pulled a similar stunt with a professional chef, asking him about a favorite recipe of hers, claiming it was a pork dish with Bearnaise sauce. This tripped up the chef because the dish in question was actually salmon. The chef was then forced to confess that he did not graduate from cooking school, which tied in with a possible motive for murder at the restaurant where he worked.
* In an episode of ''Series/NCISLosAngeles'', [[HeterosexualLifePartners Sam and Callen]] are kidnapped and trapped in a warehouse. They escape and shortly after run into a man claiming to be an abducted [[NoSuchAgency NSA agent]]. Sam secretly decides to test him by asking him which way he exited NSA HQ the day before. [[spoiler: The man answers with a route that Sam knows is blocked by construction, revealing that he's an impostor. Sam lets Callen know via TroubleEntendre, and they secretly turn the tables on him.]]
* In ''Series/{{Outlander}}'', Claire tries to bluff Jack Randall into releasing her by claiming that she also works for his patron, the Duke of Sandringham. She tries to remain vague when Randall asks her if she met the Duchess, saying that she got her orders by letter, but she's still foiled because she doesn't know that the Duke never married.
* In ''Series/{{Oz}}'', Adebisi asks undercover cop John Basil about various criminals "Desmond Mobay" should know if his identity is genuine. He slips in a name that Basil doesn't recognize, and Basil either knows he's bluffing or suspects he might be.
-->'''Desmond Mobay''': I never heard of that guy.\\
'''Simon Adebisi''': That's because I made him up.
* In an episode of ''Series/PainkillerJane'', Jane is set up by a wild scheme to give away the location of her team's secret headquarters. Part of the plot has her "rescued" by a shapeshifter posing as her best friend, Maureen. When Jane notices the woman doesn't have a recently applied tattoo, she talks of how she forgives Maureen for sleeping with a classmate in college. Later, after the shapeshifted is captured, they talk as it turns out the guy was the class geek and thus Jane knew it wasn't the real Maureen.
* In the ''Series/{{Poirot}}'' episode "Hickory Dickory Dock", one of the students professes to be an expert in Keats. When [[Literature/HerculePoirot Poirot]] quotes some poetry at her she assures him that he certainly knows his Keats. The only problem is that it wasn't a Keats poem.
* ''Series/ThePrisoner1967''
** Episode "The Schizoid Man": After a Village agent surgically altered to look like #6 is killed, #6 attempts to masquerade as the agent to escape. Unfortunately, he talks too much and makes several mistakes, causing #2 to become suspicious. #2 mentions someone named Susan saying something "only a month ago": #6 doesn't react. He asks #6 to "give Susan my regards" and #6 agrees. Later, after #6's escape has been foiled, #2 tells him that Susan died a year ago.
** And depending on which episode order you prefer, there's also #6's reaction to #2's mention of "the General" as if he's talking about a person; another episode is about a supercomputer by that name.
* ''{{Series/Probe}}'':
** [[Recap/ProbeBlackCatsDontWalkUnderLaddersDoThey "Black Cats Don't Walk Under Ladders (Do They?)"]]: During TheSummation, Austin uses the killer's own knowledge against them, causing them to believe that they've been affected by the same [[TamperingWithFoodAndDrink poisoned tea]] that was used to kill Marty Corrigan. He has to do it because until the killer confessed, he wasn't sure which of the suspects had done it.
** [[Recap/ProbeNowYouSeeIt "Now You See It...."]]: At the climax of the episode, Austin James has recreated the murder method that was used to kill the previous two businessmen. He confronts his prime suspect with the situation (which includes an [[ElevatorFailure empty elevator shaft]] covered by a {{Hologram}}) and tricks him into confessing. The murderer does, but then tosses Austin down the empty shaft. Serendip's CEO and several police come out from around corners to arrest him. (Austin is fine, having [[InsufferableGenius anticipated this]], lying safely on a crash cushion.)
** [[Recap/ProbePlan10FromOuterSpace "Plan 10 from Outer Space"]]: Because he didn't have any evidence to determine if Trish or Helga committed the murder, Austin has to trick the murderer into confessing, by using the victim's sunglasses, which he says created a photonegative when the victim was electrified. When the murderer sees herself on the wall, she immediately starts trying to defend herself.
* In an episode of ''Series/PromisedLand1996'', a photography teacher becomes suspicious of the quality of the project a student has handed in and proceeds to ask him several questions in photographer lingo. Bristling at the implication, the student proceeds to not only answer him fluently, but even offer answers that he didn't ask for, thus proving that he alone worked on the portfolio.
* ''Series/RedDwarf''
** In "[[Recap/RedDwarfSeasonIBalanceOfPower Balance of Power]]", Lister suspects that the Kochanski that visits him during his chefs exam is a fake when she uses the phrase 'up-up-up the ziggurat, lickety split' - something Rimmer has said before onscreen. To test 'her', he brings up them having had sex behind the bins on the snooker, which never happened, and causes Rimmer to blurt out that Lister never told him that.
** In "[[Recap/RedDwarfSeasonVIPsirens Psirens]]", to differentiate between Lister and a shape-shifting, brain-eating Psiren, the rest of the crew got them each to play the guitar. Lister incorrectly believed himself a [[VideoGame/GuitarHero guitar god]], so the Psiren played excellently. The crew then knew which one to blast. Although after hearing [[DreadfulMusician how the real Lister plays]], they wanted to shoot him too.
--->'''Cat:''' Little survival tip, bud. Never play your guitar in front of a man with a ''loaded gun''.
* ''Series/{{Revenge}}'': Victoria invites the fake Amanda Clarke to tea and serves strawberries. When "Amanda" eats them, Victoria recalls her having had a severe allergic reaction to strawberries as a little girl. "Amanda" claims to have grown out of the allergy, but Victoria now ''knows'' she's an impostor because she made up the whole thing.
* ''Series/{{Sanctuary}}'': Will and Helen are among the survivors of a plane crash who are being picked off one by one by a creature that can create visual illusions. They know the creature can make itself appear to be one of the survivors, but they don't know who it is. The creature lures Will out of the plane and takes on his appearance. Helen catches it when, as Will, it offers her a cup of tea and she claims to prefer coffee; the real Will would have known that Helen hates coffee.
* In an episode of ''Series/{{Sliders}}'', Quinn impersonates his double until the double's friend and villain of the week successfully bluffs him. Quinn accepts the man's invitation to go sailing; unfortunately for him, he didn't know his double was terrified of water.
* ''Franchise/{{Stargate|Verse}}'':
** ''Series/StargateSG1''
*** In an early episode, this was used to determine whether an elderly alien really was Daniel as he claimed he was. (He was)
---->'''Jack:''' What color dress was your sister wearing when I took her out last night?\\
'''Daniel-in-Ma'chello-body:''' I don't have a sister, and if I did, I'd never let her go out with you.
*** Played with in "1969", when the team has traveled back in time and [[TimeTravelersAreSpies are assumed to be spies]]. Not trusting their American accents, the interrogator asks [[CunningLinguist Daniel Jackson]], in Russian, if they are spies. Daniel answers "no", but instinctively switches to Russian as well. O'Neill is rightly annoyed.
** ''Series/StargateAtlantis'': In the season 5 premiere: [[spoiler:Sheppard does this to the people coming to dig him and Ronon out from the rubble of Michael's collapsed base. First he asks if "Harris" is there, and when someone replies in the affirmative, Ronon remembers that Harris is on leave. Then Sheppard offers to buy the rescuers drinks when they get back, asking one if he prefers [[WesternAnimation/TheSimpsons Duff Beer]] or [[Creator/OprahWinfrey Oprah Ale]]. From the rescuer's obliviousness to the fact that those are fictional beverages, Sheppard and Ronon conclude that their "rescuers" are really Michael's [[HalfHumanHybrid half-Wraith]] mooks]].
* ''Franchise/StarTrek''
** ''Series/StarTrekTheNextGeneration'':
*** In "The Arsenal of Freedom", a simulacrum of a Starfleet captain unquestioningly accepts Riker's claim that his ship is called ''Lollipop'' ("[[Creator/ShirleyTemple It's a good ship]]").
*** In "Conspiracy", an old friend of Picard's does this to Picard because of alien parasites taking over the minds of Starfleet officers, which is explained when Picard asks his old friend what the hell he's talking about.
*** Likewise, in "Allegiance", Picard mentions [[CallBack a recent, still-classified incident]] in front of a fake Starfleet cadet, knowing that a real one would have no way of recognizing the comment as anything but a meaningless name.
** ''Series/StarTrekDeepSpaceNine'': In the episode "Inquisition", while Bashir already suspects that things aren't what they seem, he proves it to himself and his captors when he asks what happened to O'Brien's shoulder, previously injured playing racquetball. O'Brien says it got better; Bashir then says it wasn't dislocated during a racquetball game, but kayaking. Holodeck room appears, Bashir's interrogator congratulates him on seeing through the illusion.
** ''Series/StarTrekVoyager'':
*** In "Renaissance Man", Chakotay makes up an incident he claims Janeway told him about. When "Janeway" claims the current crisis has nothing to do with that past one, Chakotay knows that she's a fake. (It was the Doctor being forced to act as TheMole.)
*** In "In the Flesh", having visited a functioning, holographic replica of Starfleet Academy built by aliens, Janeway reminisces about the real academy so she can casually drop in an inaccuracy to see if Chakotay has been replaced by an impostor. Chakotay is the real deal and is slightly offended.
* ''Series/StrangerThings'': Upon the discovery of Will Byers' "body", Hopper becomes suspicious of the many additional goings-on of the case, like the local coroner being sent home so someone "from state" can do the autopsy, or the location of the "body"'s discovery. So he talks to O'Bannon, the trooper who called it in.
-->'''Hopper:''' So that quarry, that's, uh, that's state-run, where they found the boy, huh?\\
'''O'Bannon:''' Yeah.\\
'''Hopper:''' ''[dry chuckle]'' Yeah, well, that's funny. 'Cause, you know, I know for ''a fact'' that it's run by the Sattler Company.
** So Hopper goes to the morgue and tries to bluff his way past the Indiana State Trooper guarding the door. The guard's insistence that he doesn't work with the trooper who called in the "body" leads Hopper to realize he's an imposter.
-->'''State Trooper:''' Hey, you can't be back here!\\
'''Hopper:''' Yeah, I just got off the line with O'Bannon. He said that he needs to see you at the station. It's some emergency ...\\
'''State Trooper:''' What the hell are you talking about? I don't work with O'Bannon.\\
'''Hopper:''' Did I say O'Bannon? I meant ...\\
'''State Trooper:''' ''(vacant, hostile staring)''\\
'''Hopper:''' ''[grimaces]'' Okay. ''(punches the trooper out cold)''
* ''Series/{{Supernatural}}'':
** In the episode "[[Recap/SupernaturalS08E21TheGreatEscapist The Great Escapist]]", ProperlyParanoid Kevin Tran grows suspicious when the apparent Winchester brothers forget the [[TrustPassword secret knock]] and sends them to get him takeout barbecue. When they obey with proper deference to a Prophet of the Lord, Kevin knows that they're Crowley's {{Mook}}s in disguise and sends them into a trap.
** Double subverted in the much earlier episode "[[Recap/SupernaturalS01E06Skin Skin]]". Sam suspects that a shapeshifter they're chasing is posing as Dean. He asks a supposedly casual question that's pretty obviously a test. The shapeshifter has access to Dean's memories and answers correctly, so Sam tosses him the car keys. However, the question was a red herring; the ''real'' test was the keys, which "Dean" caught with his left hand despite the real Dean having an injury to the left shoulder.
* In the season finale of ''Series/TeenageBountyHunters'', Sterling is with their rich mother, Debbie who says they have to leave town over her past crimes. Sterling then gets a text from sister Blair saying she's with Debbit at their house. Sterling carefully asks "what happens with Queso" and without hesitation, Debbie says Blair and their father will bring him along. Sterling literally screams "our dog's name is Chloe, who are you?!" In reality [[spoiler: this is Debbie's twin sister Dana...who also happens to be Sterling's real mother.]]
* A storyline on ''Series/ThirdWatch'' had the cops are searching for a pair of rapists who pose as police officers so that they can pull women over and then assault them. At the episodes end, as the fake cops are menacing a woman, the real cops arrive. The fake cops try to claim that the woman's screams for help are just the raving of someone high on drugs. Already suspicious (they know the woman and know she's not an addict), one of the real cops asks the fakers a question in "cop lingo". When he's unable to answer, they instantly know they've caught the criminals.
* In ''Series/TokusouSentaiDekaranger'', Hoji and a MonsterOfTheWeek switch bodies. Ban figures it out by calling Hoji "aibo" (partner). The real Hoji always says "Don't call me 'partner!'" but the villain didn't know that.
* Once in a while on the game show ''Series/ToTellTheTruth'', a panelist will ask an obtuse question to the challengers that sounds like it has something to do with the subject matter, only to find after the voting and reveal that it really didn't. Just to see if the impostors (or the real person) would give an answer.
* In ''Series/TwinPeaks'', Audrey Horne is caught out this way when she fakes her resume at One-Eyed Jack's.
* One episode of the 2009 ''[[Series/{{V 2009}} V]]'' series has Erica out James May's girlfriend as an undercover V agent using this method. They were engaging in small talk about (among other things) where she went to college, and Erica deliberately referred to the wrong football team, which exposed the alien when she failed to correct the error.
* In the second episode of ''Series/{{Waco}}'', Koresh, suspicious of his new neighbor who claims to be a rancher, asks him a question about cows. Vazquez, who is a government agent and not a rancher, fails to provide a good answer, tipping Koresh off that he's not who he says he is.
* Artie does this in an episode of ''Series/{{Warehouse 13}}'' to prove that Myka is really Alice Liddell, who has somehow swapped with Myka using a disco ball (ItMakesSenseInContext).
* In ''Series/TheWire'', Chris and Snoop find out which drug dealers are from New York and trying to muscle in on their territory by asking things only someone from Baltimore would know. Unfortunately, Snoop isn't that knowledgeable of local pop culture herself, and after she almost kills someone who gives a correct answer, Chris decides that he should handle asking the questions.
* In an episode of ''Series/XenaWarriorPrincess'', Xena identifies a supposed [[spoiler:Spartan deserter]] as a [[spoiler:Persian spy]] by asking him if he is eager to see the waterfall in his home town again. Of course, there is no waterfall.
* ''Series/TheXFiles'': In "[[Recap/TheXFilesS06E20ThreeOfAKind Three of a Kind]]", this is actually used against the Lone Gunmen when Byers is attempting to pass himself off as a defense contractor. One of the other players at the poker table asks him a question: Langley, who has been providing research and info to support Byers' masquerade, comes up empty and tells Byers to fold. Byers, unfortunately, is feeling too bold for his own good, and exposes himself with a blatant lie.

[[folder:Podcasts]]
* Podcast/DiceFunk: Rinaldo does this to [[spoiler:the fake lord's son by referring to a non-existent deceased aunt.]]
[[/folder]]

* In the ''Radio/AdventuresInOdyssey'' episode "Sheep's Clothing", a suspicious pastor asks "Paula Jarvis" (who has already slipped a few times) about the annual blueberry festival from where she supposedly grew up. He doesn't mention that they actually grow strawberries there...
* [[MysteryWriterDetective Paul Temple]] and his wife Steve sometimes use this to subtly reveal impostors.
** In "Paul Temple and the Gilbert Case", concerned for the safety of his wife, they agree on an arbitrary question/answer which only they will know, and which she can use to challenge any telephone caller claiming to be him. When Steve first uses the question, the caller really is Paul (although there's a [[CliffHanger cliffhanger]] before he answers, which initially makes it seem like he's an impostor); the second time is a subversion, but on a subsequent occasion, in "Paul Temple and the Conrad Case", it's successful in revealing an impostor.
** Also in "The Gilbert Case", Steve herself is bluffed by the owner of a nightclub who mentions a "lifelong friend" of the person whose membership has allowed Paul and Steve into the club (and who is actually an undercover detective). Steve says that she knows the friend well, but finds out soon after that he doesn't exist. Needless to say, she has a mild OhCrap moment when she realises she's been had, although it turns out that the owner knows about the detective anyway.
** In a second example from "The Conrad Case", Temple speaks to Elliot France, another author, over the telephone, and congratulates him on the success of his book "Zero is Tomorrow" -- "France" thanks him, but the title is actually that of Temple's next, as yet unpublished, novel.

[[folder:Myths & Religion]]
* A variant occurs in ''Literature/TheOdyssey'': Penelope uses this to see whether the man claiming to be Odysseus after 20 years really is her husband. She orders their bed to be prepared and placed outside the bedroom; Odysseus protests that this couldn't be done as he carved the bedpost himself out of a living olive tree still rooted in the ground, thus proving his identity. Making this one OlderThanFeudalism.
* Literature/TheBible
** Samson gives Delilah false information whenever she asks about his weakness. In a subversion of this trope, Samson doesn't seem to cotton on to her plot even when the Philistines try to kill him by exploiting the exact same false weakness he just told Delilah. Eventually, he tells Delilah his ''real'' weakness anyway, [[TooDumbToLive which gets him blinded and enslaved.]]
** Also, the Gileadite trap for Ephraimite spies in Judges 12. The Ephraimites were unable to pronounce "sh" properly, so the Gileadites used the word "shibboleth" as a password -- if you couldn't make the sound correctly, and rendered the word "sibboleth", it was definitely not your lucky day...

[[folder:Theatre]]
* In ''Theatre/TheBat'', Brooks claims to be the new gardener, but does not seem to know that [[http://en.wikipedia.org/wiki/Measles rubeola]], [[http://en.wikipedia.org/wiki/Alopecia alopecia]] and [[http://en.wikipedia.org/wiki/Urticaria urticaria]] are not in fact hardy perennials.
* Inverted in ''Theatre/DeathAndTheMaiden''. Housewife Paulina recognizes her houseguest's voice as that of her unseen captor when she was a political prisoner. Paulina's husband Gerardo doesn't believe she is correct; he gets her to tell him the detailed story of her captivity, torture, and rape, then feeds it to the other man, Roberto, so that Roberto can deliver the "confession" Paulina claims will satisfy her. However, Paulina suspected the men planned such a ruse, and she deliberately peppered her account with minor inaccuracies. After Roberto makes his statement, Paulina announces that he has corrected those details, and she is more convinced than ever of his guilt. The play never actually reveals whether or not Roberto was truly Paulina's captor, though the [[Film/DeathAndTheMaiden film adaptation]] makes it explicit that he was.

[[folder:Video Games]]
* In ''VideoGame/ProfessorLaytonAndTheCuriousVillage'', the protagonists get suspicious about [[spoiler:Inspector Chelmey]] when they find a newspaper article mentioning the man's love for sweets when previously he had violently objected to being served tea and cakes. They question him about this and mention his wife's name... only they give the wrong name, and he proceeds to parrot the mistake, exposing himself as an impostor.
* Played with in ''VideoGame/Fallout2'' by Renesco the Rocketman when you're looking for parts. After giving the password, you're asked for the second password - your only response is to cuss out the foreman for not giving you the second password. Renesco then says to relax, that there was no second password. Humorously, if you leave this quest on the backburner for too long, you can forget the first password too...
-->'''The Wanderer:''' Marcus says... shit...\\
'''Renesco:''' "Really? I'm sure he didn't send you all the way down here to say "shit".
* An interesting case in ''VideoGame/DragonQuestVI''. The Hero enters Somnia Castle in the other world after discovering you look exactly like the missing prince. The chancellor, having heard that someone in town purchased noble clothes like what the Hero is wearing and he asks the name of your long dead sister. [[spoiler:''All'' of the available choices are wrong. Then again, it turns out that the Hero ''is'' the Prince of that world's Somnia...[[LiteralSplitPersonality sort of]].]]
* A body-snatcher variant appears in ''[[VideoGame/MegaManBattleNetwork4RedSunAndBlueMoon Mega Man Battle Network 4: Blue Moon]]'', in which Lan got suspicious when Mega Man tells him to forfeit the tournament. So Lan decided to quiz him, and the player selects the answers. For the first couple of questions, it's entirely possible to get the question ''right'' (subverting the trope), but then Lan throws out a question about the strongest Navi Mega Man has ever faced, and none of the choices given have actually existed in the series. This allows Lan to determine that Junk Man is controlling Mega Man's body. Interestingly, there ''is'' a question about Lan's TrademarkFavoriteFood, but while the canon answer should be "curry" (which isn't a choice given), [[DubInducedPlotHole in the English version]] the correct answer is "hamburgers".
* In ''VideoGame/InjusticeGodsAmongUs'', the "main" universe Cyborg infiltrates the parallel universe Regime by posing as his own counterpart. Regime!Catwoman notices something is off with him, and starts acting as though the two of them have been having an affair. When he tries to play along, she knows he's a fake.
* In ''Jolly Rover'' James tries to pass himself off as a pirate named Davey and is promptly stumped by Melvin asking where he and Davey were when they got drunk on a keg of rum and thought they were two young princes. It takes the help of a parrot to get past this point.
* In a ''VideoGame/Yakuza6'' sidequest, Kiryu receives a call from a scammer pretending to be Taichi, one of his wards at his orphanage in Okinawa, who asks that Kiryu give a large sum of money to an accomplice in the name of helping a sick friend. Smelling a rat, when Kiryu goes to meet with the accomplice he pointedly asks if "Taichi" ever mentioned how he got the "huge burn scar" on his face (which, of course, the real Taichi doesn't have), and is almost dumbfounded at how quickly the scammers exposed themselves.
** The next game, ''VideoGame/YakuzaLikeADragon'', has the assasssin Mirror Face perfectly disguise himself as Adachi while attacking the real one. Ichiban asks them some questions about traffic laws, where one of them is clueless while the other gives out the correct answers. Ichiban then attacks the latter, which turns out to be Mirror Face after all, who complains how the real Adachi could have ever worked at the DMV with such incompetence.
* ''VideoGame/TalesOfBerseria'' has a moment when Eizen (seemingly) finds his captain, Van Aifread, being held hostage. Eizen engages in some CasualDangerDialog about his absence and mentions his brother; Aifread purports to remember discussing that topic, and gets [[BareFistedMonk a fist to the chest]].
-->'''Eizen:''' I've got no brother.
[[/folder]]

[[folder:Visual Novels]]
* Late in ''VisualNovel/{{Tsukihime}}'', in a moment of uncharacteristic brilliance, Shiki inserts an incorrect detail into the story of how he received the ribbon he promised to return to its owner when he left the Tohno mansion. [[spoiler:Hisui does not spot the detail, however, which lets Shiki figure out the TwinSwitch, and that the twin who watched him from the window is actually the StepfordSmiler Kohaku.]] Since the reader already knows the truth from one of the previous routes, it is not a big surprise, but it does alter how the story unfolds after that point.
[[/folder]]

[[folder:Web Comics]]
* Casper uses this on "Komi" in ''Webcomic/{{Darken}}''. [[spoiler:It works, but Casper finds himself in a less than ideal situation as a result.]]
* ''Webcomic/GirlGenius'':
** Agatha uses this tactic to sound out whether Othar is the real deal. (He is.)
** Later, the Heterodyne's seneschal Carson von Mekkhan uses a variant on the same trick to test whether Agatha really has a Heterodyne heritage or not. (She does, but her performance fails to entirely convince him.) Eventually Agatha got tired of the questions and started telling him things that only a real Heterodyne should know, which caused him to end the interview and move on to the next stage of confirming her heritage.
* In ''Webcomic/GeneralProtectionFault'', Nick uses this to confirm whether he's dealing with the real Ki or not shortly after he's been kidnapped [[spoiler: into what turns out to be the Negaverse. Nega-Ki gets the name of a place in an unfinished novel of Ki's wrong, which proves to Nick she's not ''his'' Ki]].
* Played with in [[http://wondermark.com/507/ a comic]] from ''Webcomic/{{Wondermark}}''.
* ''Webcomic/BasicInstructions'' [[http://basicinstructions.net/basic-instructions/2006/7/9/how-to-prove-which-of-you-is-the-evil-twin.html recommends this over]] KillUsBoth when dealing with an EvilTwin, as it has less of a chance of backfiring.
* ''Webcomic/{{Narbonic}}'':
** Madblood uses this to prove that the disguised Dave isn't really him from the future.
-->'''Dave:''' Yes, Lupin of the past, I've long ago solved all your petty problems.\\
'''Madblood:''' Ah, good! You can tell me how to correct the degradation of 500th-generation molecular cascade patterns on my liguid-crystal microcircuitry!\\
''([[BeatPanel beat]])''\\
'''Dave:''' Should I save us some time and admit I'm not actually you?\\
'''Madblood:''' That'll do nicely. I have no idea what I just said anyway.
** Later on, Helen immediately spots Madblood (disguised as Dave) as an impostor, and decides to mess with his head by pretending she and Dave had an affair, which Madblood is forced to play along with.
* In ''Webcomic/{{Visseria}}'', done by a nameless guard to Jack after he casually mentions a nearby residence that he's supposedly leading the guard to.
-->'''Guard:''' The Jaerock Boarding House?\\
'''Jack:''' That's the one! ... Is something wrong?\\
'''Guard:''' There's no such thing as Jaerock Boarding House.\\
''([[BeatPanel beat]])''
[[/folder]]

[[folder:Web Original]]
* In ''Defenders of Stan'', ButtMonkey Stan has a death ray pointed at two guys. One is his {{jerkass}} brother, Ted, and the other is his brother's evil robot clone. Stan says, "I love you, Ted." The robot clone says that he loves him too while his brother laughs and calls him gay.
* ''WebAnimation/MinilifeTV'': In "[[Recap/MinilifeTVSeason5Episode12 The Vampodcast]]", Zach disguises himself as a zombie to gain access to the Burton Night Club, a monster-exclusive club, to help Snowball the vampire with his podcast. When they interview Arnold the Butcher Zombie, Arnold accidentally electrocutes Zach by spilling some water on the microphone, which causes him to react in pain. Arnold points out that zombies aren't supposed to feel pain and throws his mug at Zach to get him to react in pain again.
* [[Website/NotAlwaysRight Not Always Romantic]] features a story where [[https://notalwaysright.com/its-an-ex-tra-small-world/41319/ one woman and her sister]] use this to catch [[ClingyJealousGirl her husband's ex]] in a lie.
** Website/NotAlwaysRight's main archive has [[http://notalwaysright.com/how-to-scam-a-scammer-part-3/242 this lovely story]], where a scammer tries to claim they weren't delivered any of the items they ordered. The cashier follows along until calling them out at the end.
* When ''WebVideo/TheAngryVideoGameNerd'' and ''WebVideo/TheNostalgiaCritic'' do battle, the Critic finds himself hopelessly outgunned by all of the Nerd's NES accessories and, while cowering behind a box, tries to save himself by claiming he's the Nerd's brother. The Nerd immediately sees through it and challenges him to say their mother's name.
--> '''Critic:''' Of course I know the name of our mother! Uh, Eliza... be-- (Gun gets shoved in his face) OH BLAME A GUY FOR TRYING!
[[/folder]]

* ''WesternAnimation/TheBeatles'' episode "No Reply" had the boys on vacation in Hawaii where there are suddenly two Pauls. One of them is a criminal master of disguise named Anyface, and nobody can tell who is who until a bevy of fangirls show up. The impostor does not run.
* ''WesternAnimation/FamilyGuy'':
** Spoofed in the episode "German Guy": when Chris discovers that his new elderly friend Franz is a former SS officer, Franz holds Peter at gunpoint, but Peter knocks his gun out of his hand, allowing Chris to get it. [[FatIdiot Chris]] suddenly thinks that Franz is Peter's EvilTwin and asks them what's his birthday. Franz answers correctly and Chris shoots Peter and hugs Franz, who takes back the gun. Peter rightfully calls Chris out for his incompetence, [[NeverMyFault but Chris argues that he should've learned his birthday]].
** The episode "The Hand That Rocks the Wheelchair" has Stewie trying to undo his in-universe VillainDecay, but instead accidentally makes himself an EvilTwin. When the two fight at the episode's climax, they remove each other's clothes and entrust Brian to shoot the right one. Brian remembers that the real Stewie is amused by the sight of his own feet and shoots the one who doesn't laugh at them, but the episode ends with a parody of the ending of "Music/{{Thriller}}" that implies he killed the original ([[SnapBack for that episode]]).
* Hilariously overblown in ''WesternAnimation/FantasticFourWorldsGreatestHeroes'' "[[Recap/FantasticFourWorldsGreatestHeroesMyNeighborWasASkrull My Neighbor Was A Skrull]]" when shapeshifting aliens are posing as ''every single one of the heroes' neighbors and acquaintances.'' Reed Richards starts asking questions like "Do you remember when we first met? Was it... five hundred years ago? On the moon? Remember, you flew up there in your bathtub?" and "I always loved your wings, Mrs. Smith. They're so white and fluffy. Would you show them to me, please?"
* In the ''WesternAnimation/{{Futurama}}'' special ''Bender's Game'', Larry, Walt, and Ignur turn up at Planet Express dressed as owl exterminators, in an attempt to steal the Anti-Crystal. [[TooDumbToLive Fry falls for it]], but Farnsworth sees through them immediately and presents them with an owl. They hilariously fail to exterminate it and their cover is blown.
* In the ''WesternAnimation/GIJoeARealAmericanHero'' episode "Cobra's Creatures", the Joes attempt to stop Dr. Lucifer by having Scarlett impersonate Dr. Atilla, a scientist he has feelings for. Dr. Lucifer suspects that something is amiss and asks the disguised Scarlett if she remembers when he proposed to her. Scarlett answers that she does remember, which confirms Dr. Lucifer's suspicions that she's an imposter, revealing that he ''never'' proposed to Dr. Atilla.
* ''WesternAnimation/HarleyQuinn'': When Harley decides to rob Maxi Zeus, she has [[VoluntaryShapeshifter Clayface]] act as a distraction. As Clayface in this version is a ridiculously over-dramatic would-be actor, he makes up an absurdly elaborate cover story about being Maxi's long-lost son from a one-night stand that Maxi had decades ago. Maxi gets suspicious and asks how it is that his "son" didn't inherit his mother's bright blue eyes, at which point Clayface changes his eye color (which had matched Maxi's) to bright blue. [[ExaggeratedTrope Maxi then proceeds to bluff him with a ridiculous list of various traits that Clayface "should" have inherited]], with Clayface changing to add each one. By the time Maxi calls the thing off, Clayface has turned himself into a lisping, hunchbacked, grotesquely deformed freak.
* In one episode of ''WesternAnimation/{{Ninjago}}'', Lord Garmadon creates evil clones of the ninja team. When Sensei Wu meets the impostors, he becomes suspicious of them and remarks that Lloyd must be having fun at the amusement park they left him at. The fake ninja go along with the amusement park story, unaware that Lloyd is actually at his old boarding school with the real ninja, proving to Wu that they're fakes.
* In the Hub's ''[[WesternAnimation/PoundPuppies2010 Pound Puppies]]'', Squirt trades places with pampered house pet Cuddlesworth in "The Prince and the Pupper", and meets Cuddlesworth's fellow pet, a Persian cat named Madame Pickypuss. Pickypuss manages to confirm that Squirt is an impostor when he accepts a treat that she knows her friend Cuddlesworth hates.
* In ''WesternAnimation/TheRealGhostbusters'', Egon bluffed a Janine imposter by referring to his mother as his Aunt Helga. The real Janine would recognize Egon's mother because they've met before.
* In the ''WesternAnimation/RegularShow'' episode "Temp Check", a temp that Rigby hires turns out to be a shapeshifter that gradually changes until it's impossible to distinguish between the two of them. The attempt to get the impostor to expose himself by asking questions fails, so Mordecai offers the winner of the challenge a hug. "Rigby" takes it, which outs him as the impostor (since, earlier in the episode, it's shown that Mordecai and Rigby would never hug one another.)
* ''WesternAnimation/SonicTheHedgehogSatAM'' Tails warns Sonic that the Sally at present was an imposter, but he doesn't believe him. Not at first, anyway. Sonic later bluffed Sally with a long and rather complicated handshake that they tended to use. However, he changed the last part from a thumbs-up to a thumbs-down. When Sally followed along and didn't correct him, Sonic realized Tails was right and revealed that she was a robot while the real Sally was captured.
* In the ''WesternAnimation/TransformersPrime'' episode "[[Recap/TransformersPrimeS1E8ConJob Con Job]]", the Decepticons employ a superlative shapeshifter Transformer called Makeshift to impersonate Bulkhead's Wrecker buddy Wheeljack, who then infiltrates the Autobot base. Bulkhead suspects something's wrong all through the episode, and finally forces 'Wheeljack' to tell the story of a famous battle. Makeshift talks about a fight alongside Bulkhead and the other Wreckers, and at first it looks like he gets it right, but...
-->'''Bulkhead:''' Yeah, that's exactly how it happened, except for one little thing: ''I wasn't there.''
* In ''WesternAnimation/ThunderbirdsAreGo'', the main characters unmask an AI pretending to be one of their siblings by asking if he misses their LethalChef grandmother's cookies. When "he" says yes, they immediately know they're not actually talking to him.
* In ''WesternAnimation/TUFFPuppy'', The Chameleon got into a tussle with Dudley, while disguised as Dudley, Kitty was able to tell who was the real Dudley by getting one of them to spell Dudley's name, the Chameleon got it right and she blasted him. The real Dudley can't spell his own name, let alone write it down.
* In the ''WesternAnimation/WildWestCOWBoysOfMooMesa'' episode "Stolen on the River", Cowlorado Kid infiltrates a luxury riverboat cruise, in an attempt to nab notorious outlaw and gambler Five Card Cud. Five Card questions his cover story: if Kid is such an accomplished high roller, surely he knows Snake Eye Smithson? Kid claims he won a bundle off Smithson just last week, confirming Five Card's suspicions. After all, Smithson has been dead for over 10 years since Five Card killed him himself.
[[/folder]]

[[folder:Real Life]]
* In UsefulNotes/WorldWarII: A variation for those on watch both used and inverted this system: The guard would state "The Land of the Free," to which an American would reply "And the Home of the Brave." Then the guard would state "The Terror of Flight," to which a German would reply as "And the Gloom of the Grave"... Every American soldier would [[TrustPassword know the first verse of their national anthem]], but only a spy [[INeverSaidItWasPoison trying too hard to pass as one]] would know the ''third'' verse.
* Similarly, German soldiers would allegedly wish people "Good luck" at checkpoints or gates in English, in order to single out Allied troops DressingAsTheEnemy. It's so hardwired into us to respond in kind that Allied troops would spontaneously blow their cover by responding with "thank you" or "you too" ''also'' in English.
* El Al security guards ask similar questions of the airline's passengers. For example, they might ask if the passenger saw a sporting event that didn't actually happen. If they say "yes" it's a good sign they're hiding something.
* To shortstop this trope, India-based workers who do tech support for American companies will sometimes have current weather information or sports information up for whatever American city they claim to be in.
* Psychological inventories often include questions asking if the person is a fan of made-up people to see if the person is lying or not bothering to read the questions.
* A woman named Shellie Kepley became concerned because she could not reach her father, Paul Gruber, despite the fact that he continued to send her greeting cards for various holidays and events. However, she had noticed that his signature was different. The next time she called him and left a message, she reminded him of her son's upcoming birthday, as well as the money he had promised. Sure enough, she promptly received a card with a check for $25. However, this only ''confirmed'' her suspicions that something was wrong, as it was NOT her son's birthday, nor had she asked him for any money, both of which her father would have known. Police eventually found that a local handyman, Darryl Kuehl, had befriended Gruber before murdering him to gain access to his bank account and was keeping up the illusion of him being alive by continuing to pay his bills and send letters and cards to his family.
[[/folder]]

!!Subversions
%% If the bluff "fails" because the target is genuine, that is *not* a subversion--it's a straight example and belongs in the above section.

[[folder:Anime & Manga]]
* ''Manga/DeathNote'': L does this to Light quite a bit to see if he slips up by saying something only Kira would know. For example, showing him three suicide notes Light had some criminals write and seeing if he can find the secret message Kira inserted into them to taunt L, who has intentionally given Light the notes in the wrong order. However, Light is also a supergenius, and quickly figures out what L is up to, and hence doesn't expose himself (by putting the notes into the right order or being surprised when L introduces a fake note to the mix). Partially subverted anyway. It takes a bit for Light to realize that the fake note makes sense, and L ends up being slightly more suspicious of Light than he was before the test.
* In ''Manga/YuYuHakusho'' the heroes are told that one of them was replaced by an impostor who knows ''everything'' about the replaced person making this trope unusable. Though Yusuke still tries asking Botan her three sizes. ''Because'', of course, she'd never told him.
* In ''Manga/CatEyedBoy'', the title character shapeshifts himself into the form of a young boy to tease him. When the mother discovers this, she demands to see a birthmark she claims the boy has, and Cat-Eyed Boy assumes it's an example of this... so is the one of the pair not to have the very real identifying birthmark. Oops.
* ''Anime/{{Bakugan}}: Gundalian Invaders''. Suspicious of Jake's sudden escape from Kazarina, Shun tests him by mentioning the operation Jake participated in an earlier episode. He correctly replies that he didn't take the major role (Dan and Shun did). However, Jake was in fact brainwashed by Kazarina; [[DefiedTrope she kept his memory intact]].
[[/folder]]

[[folder:Film]]
* ''Series/KnightRider'': In the 2008 movie, Sarah Graiman is accosted by a security guard during her escape from a pursuer. KITT warns her that the guard may in fact be a fake, and Sarah tells the guard about where she was going -- except all of the locations she lists don't exist. The guard [[spoiler:-- who ''is'' a fake --]] catches on, however.
* ''Film/OceansEleven'': Terry Benedict, the owner of the casino the gang are trying to rob, tries this on Linus, who's disguised as a member of the Nevada Gaming Commission. It doesn't work, since [[spoiler:Linus also has a VoiceWithAnInternetConnection feeding him info]].
-->'''Benedict:''' You new at the commission?\\
'''Linus:''' Been there about two years.\\
'''Benedict:''' I know Hal Lindley over there; you work with him at all?\\
'''Linus:''' ''({{beat}})'' Not since he died last year.
* In ''Film/CatchMeIfYouCan'', Frank (posing as a lawyer) claims to have been taught by a professor who also taught his girlfriend's father, and her father asks what the professor's dog's name was. Frank, smelling a trap, replies simply that the dog had since died. The father remains suspicious.
* In ''Film/KingdomOfHeaven'', when Balian meets his father's knights, one of them tries to discern if he really is his son. After mentioning the height, the knight goes on about the eye color of his liege, which is promptly corrected by Balian, thereby proving that he did the research, at least.
* In ''Film/DieHard'', John encounters Hans alone on one of the upper floors. Hans quickly pretends to be an escaped hostage, speaking in a convincing American accent instead of his usual British (well, German-ish). John introduces himself, glances at a nearby office directory and asks Hans for his name. In this case, CrazyPrepared Hans gave a name from the directory, Bill Clay. John still somehow sees through it -- a deleted scene shows he recognized the watch Hans was wearing, because it matched some of the other terrorists.
* A variation in ''Film/MyCousinVinny''. During the climax, Vinny puts his girlfriend Mona on the stand as an expert witness. The prosecutor demands to test her claim as an automotive expert. He asks her a question about a specific feature on a very specific model of car, and she protests that it's a "bullshit" question. He assumes it means she's faking her expertise and tries to call her out on it. She responds that the model of car he was asking about didn't have the feature he asked about at all, then names the closest model that would actually have the feature and answers it correctly.
* ''Film/{{Coneheads}}'': Beldar and Prymaat Conehead are aliens from the planet Remulak, though they tell everybody that they come from France. So, as INS agent Gorman Sneedling meets them, skeptical of their claims, he asks a question in French, prompting Beldar to answer perfectly fluently, thwarting Sneedling's suspicions (at least, for the time being).
[[/folder]]

[[folder:Literature]]
* ''Literature/{{Discworld}}''
** ''Literature/InterestingTimes'': Rincewind, trying to hide his foreign origins on the highly-xenophobic Counterweight Continent, is asked by a suspicious restaurateur about a specific man on a specific road. He quickly declares he's never heard of the man or the road... only to find out the man is a high-ranking government official that everyone would need to deal with and the road is the main street through the capital. It works out, however, as the restaurateur is the local equivalent to CMOT Dibbler and is quite pleased to meet a foreigner.
** In ''Literature/{{Night Watch|Discworld}}'', Vimes has to impersonate his (now dead) mentor John Keel in the past. His knowledge of Keel, combined with his knowledge of the events at the time and some information from the Monks of History, lets him answer the interrogating officer's questions better than the officer himself could. The interrogator assumed that the impostor is a criminal, so he starts off with questions meant to trip up a civilian and not someone who actually served as a policeman during that time. Before he can try more personal questions Vimes has him so browbeat that he does not realize that Vimes says the wrong amount when speaking of his promised wages. Vimes uses this to get more pay and a higher rank.
* In Jean M Auel's ''Literature/EarthsChildren'' books, Ayla is asked about the leader of the Mamutoi tribe which she tells them she has been adopted into, but she knows the fake name (Lutie) for what it is and gives the correct information ("Tulie").
* In ''Literature/TheLongGoodbye'', when a woman is giving a confession that Marlowe doubts, she talks of dumping a suitcase full of incriminating evidence in a reservoir and Marlowe asks her how she got it over the fence. She blusters about adrenaline and then Marlowe reveals that there is no fence. After she breaks down he admits that he's never been there and really doesn't know about fence or no fence. He just thought she was lying.
* In Stephen Fry's ''Literature/MakingHistory'', the agents try to crack Michael's story by asking him if the man he claimed to see on a train had a white or gray beard. He says that the man was clean-shaven, which turns out to be the correct answer.
* In Creator/IsaacAsimov's ''The Union Club Mysteries'', the protagonist subtly interrogates a possible spy by playing a word-match game. After several iterations, the protagonist uses a phrase from the third verse of "The Star-Spangled Banner"; the spy promptly gives the phrase that immediately follows it. The protagonist concludes that, since real Americans only know the first verse (except himself, because he knows everything), the other man is actually a spy who was trained a little too well. (Asimov was a huge proponent of knowing the entire National Anthem.)
* In ''Literature/{{Trainspotting}}'', at a job interview Renton claims to have gone to a posh secondary school, which the interviewer also went to. The interviewer then asks him if a particular teacher is still teaching there. Renton, sensing a trap, simply laughs and says "God, you're taking me back now!"
[[/folder]]

[[folder:Live-Action TV]]
* In an early episode of ''Series/BurnNotice'', Michael Westen tries to get close to a ConMan named Quentin, and as part of his cover ID he claims that after Quentin got out of prison Michael wound up sharing a cell with Quentin's former cellmate, Paco, and it was Paco who recommended that Michael work with Quentin someday. When Quentin tests Michael's cover ID, he asks about Paco's prison wine, and Michael replies "Paco doesn't drink. What are you trying to pull on me?" He and Sam lampshade this and how Michael had a GutFeeling that Quentin was testing him and just took a shot in the dark.
* ''Series/MysteryScienceTheater3000''
** When Tom Servo's evil pod clone shows up, Crow tries to discern which Servo is the real one by asking about the type of condiment Crow poured into his shoes -- despite Servo having no feet -- the previous week. The real Servo forgot, and the fake one correctly guesses "Was it... Ketchup?"
-->'''Servo:''' Damn, you ''are'' me!
** Mike pulls it off by asking about Servo's collection of boxer shorts. Pod!Servo thinks ''this'' is another trick, until Servo rattles off his entire inventory in enough detail to drive the clone away in fear and "self"-loathing.
-->'''Crow:''' Frankly, I don't see why we need any Servo at all.
* In ''Series/PrisonBreak'', Charles' first conversation with Michael is along these lines when Michael claims to have known his wife, but fails to trip him up.
* There was a scene, possibly from the short-lived '90s TV series ''Probe'', in which the hero is trying to figure out which of two men is a Soviet spy, by quizzing them about obscure sports trivia. He unmasks the spy because the guy had prepped ''too thoroughly'' for his mission and was too knowledgeable.
* In ''Series/{{Medium}}'', when Ariel's body is possessed by the spirit of a murdered woman, Joe tries to pull this trope by suggesting an idea for her birthday party, and deliberately giving the wrong month. However, the woman in Ariel's body is prepared by now (not in the least because in a fit of desperation, Allison suggested, ''in front of "Ariel"'', that Joe ask her something only the real Ariel would know) and knows when Ariel's real birthday is (presumably from looking at her student ID). She calls him on his error, and he covers up by claiming that it's hard to keep track of everyone's birthday when you have three kids.
* ''Series/{{Leverage}}'': Sophie is nearly outed when the mark asks her if she's familiar with a certain person. Nate smiles and tells her (on her earpiece) to reply that the man is dead, which satisfies the mark. This is a bluff on Nate's part, though, as Hardison only confirmed the information several seconds later, which would've been too late for Sophie.
** For her part, Sophie tries to be as vague about it as possible invoking NeverSayDie:
---> '''Sophie:''' I'm so sorry. It was a beautiful ceremony.
* ''[[Series/{{Blackadder}} Blackadder Goes Forth]]'': In "[[Recap/BlackadderS4E5GeneralHospital General Hospital]]", Blackadder does this when hunting a German spy in WWI. He unmasks the spy by asking the suspect if her boyfriend had been to one of the great universities: Oxford, Cambridge, or Hull. Any real Briton would have known that only two of those are great Universities -- as General Melchett remarks, "That's right! Oxford's a complete dump!" Anyway, it goes fine until it's revealed that the suspect wasn't the spy after all.
** Again in ''[[Recap/BlackadderSS2BlackaddersChristmasCarol Blackadder's Christmas Carol]]'', when Pigmot asks the future Blackadder if he vanquished the Nibble-Pibblies, and the General replies "No, because you just made them up."
* An episode of ''{{Series/Fringe}}'' has Peter and Olivia infiltrating a black market biological weapons deal with an NSA agent who's been working the case feeding Olivia information through an ear bud to get around testing questions about people they should know if they are who they say they are. But Peter -- who doesn't have an ear bud -- is eventually asked where he met a particular individual. Olivia, with the agent's help, chimes in that they would have met at Oxford but when asked exactly where the two met neither Olivia nor the agent can help. At which point Peter, being well-traveled and brilliant, [[AssPull completely]] [[IndyPloy improvises]] a description of the scenario using his knowledge of restaurants in the area.
* "The Mind of Stefan Miklos" episode of ''Series/MissionImpossible'' had foreign spy Simpson try to determine if the man he was talking to was really Stefan Miklos. Rollin, impersonating Miklos, not only corrected Simpson's false statements but then feigned irritation that Simpson, who was being investigated, had the gall to test Miklos.
* In the ''Series/{{Angel}}'' episode "[[Recap/AngelS02E08TheShroudOfRahmon The Shroud Of Rahmon]]", Angel acts like a FanBoy to an incoming vampire and asks, "What's the password?" When the other guy says, "Password? There is no password." Angel stakes him, muttering, "Good, just checking," and goes on to impersonate him.
* ''Franchise/StarTrek'':
** In the ''Series/StarTrekTheNextGeneration'' episode "[[Recap/StarTrekTheNextGenerationS6E13FaceOfTheEnemy Face of the Enemy]]", Troi is forced to impersonate Major Rakal, a Romulan [[SecretPolice Tal Shiar]] [[ThePoliticalOfficer officer]], aboard a Romulan Warbird. The Warbird's commander, Toreth, [[JurisdictionFriction already distrusting of Tal Shiar officers]], tries to pull this on Troi by asking about Rakal's life story, e.g. where she went to school. Troi gets out of this [[DispenseWithThePleasantries by telling Toreth to just get to her point]].
** In the two-part episode "[[Recap/StarTrekTheNextGenerationS5E26S6E1TimesArrow Time's Arrow]]", Data passes himself off in 19th-century San Francisco as a Frenchman. One of the locals knows French, and speaks to Data in it. Data, [[OmniscientDatabase having apparently stored many languages in his neural net]], replies in the same tongue.
** In the ''Series/StarTrekDeepSpaceNine'' episode "[[Recap/StarTrekDeepSpaceNineS02E14Whispers Whispers]]", Bashir is performing a medical exam on [[spoiler:Replicant O'Brien]], who's quite irritated at the length of the exam. Bashir wraps up by asking if his parents are in good health. Bashir knows that the real man's mother died two years ago and is hoping to goad the imposter into a wrong answer. But the replicant, having all of [[spoiler:O'Brien's]] memories, snaps that Bashir knows full well that his mother is dead.
* In ''Series/{{House}}'', Taub pretends to have started playing racketball regularly with Wilson, but House is almost certain he's lying and quizzes him on the sport. It's almost a double subversion in that House knows that Taub knows House is applying the trope (see the example below), but since Taub's answer was correct, he hasn't really caught him out.
-->'''Gregory House''': Is a Z shot an offensive or defensive shot?
-->'''Chris Taub''': Both.
-->'''Gregory House''': You suspected that was a trick question.
-->'''Chris Taub''': But I could have said neither.
** There's a double subversion in another episode when House suspects Cuddy is feigning interest in an artist.
--->'''Gregory House''': Do you prefer the pop stuff or the Venezuelan stuff?
--->'''Lisa Cuddy''': That's a trick question.
--->'''Gregory House''': Yes, but you don't know ''how'' it's a trick question.
* In ''Series/{{Arrow}}'', during a flashback to his time on the island Oliver, impersonating one of Fyers' soldiers, is subjected to this with Fyers asking what boat he came in on, knowing that every soldier who comes to the island does so by airplane. {{Subverted|Trope}} in that Oliver manages to beat the bluff, but Fyers is actually already aware of who he is anyway.
* In a ''Series/KeyAndPeele'' sketch, a Nazi officer "tests" our two leads to see if they are "Das Negros" hiding somewhere in the neighborhood with some truly bizarre and baseless "tests" that they show no real trouble with. However, as he is about to leave ''again,'' it seems like one of them, alias Baron Helmut Schnitzelnazi, might actually be in trouble when he asks about his fellow Schnizelnazi relatives from another part of the country, and about Aunt Frieda in particular.
-->'''Officer:''' How's your Aunt Frieda?\\
'''Baron Helmut Schnitzelnazi:''' Aunt Frieda? She... is... still... [guessing] ''...fat?''\\
'''Officer:''' I don't recall her being fat. [ominous beat] But who looks like they did in college anyway?
** ...and he leaves for real shortly afterward. Apparently he just thought he'd ask.
* In ''Series/{{Charmed|1998}}'', when Piper is possessed by a demonic spirit, the possessing spirit cannot access any of Piper's memories but can communicate with the real Piper's consciousness when looking at a reflective surface such as a mirror. The real Piper takes advantage of this by repeatedly withholding key details or intentionally feeding the spirit false information in attempts to trick her into blowing her cover. It finally works when Piper tricks the spirit into addressing her boyfriend, Leo, by the wrong name, tipping him off that she isn't the real Piper. However, the spirit catches on quickly and knocks Leo unconscious before he can take any action against her or alert the other sisters.
[[/folder]]

[[folder:Radio]]
* In ''Paul Temple and the Gilbert Case'', Temple and his wife agree on a question/answer which only they will know, and which she can use to challenge any telephone caller claiming to be him. In a later series - "The Spencer Affair" - they decide to use it again, but unfortunately, [[spoiler:the bad guys have bugged their conversation]]. When 'Temple' next telephones, 'he' even goes so far as to remind her to use the secret question, which is then answered correctly.
* In one episode of ''Radio/JohnFinnemoresSouvenirProgramme'', Patsy Straightwoman attempts to enter the special caff on ferries that's only for lorry drivers by pretending to be a lorry driver on her way to Portugal. The lorry drivers guarding the door are not convinced, but are particularly clueless about testing her ("What colour is your lorry?" "Blue." "Ooh, some lorries ''are'' blue."), culminating with:
-->'''Lorry driver''': If you're going to Portugal, you must know my friend ... Pedro?\\
'''Patsy''': Yes. I do.\\
'''Lorry driver''': Well when you see him, tell him Steve says hi.\\
'''Patsy''': Will do.\\
'''Lorry driver''': Ha! You just gave yourself away, little lady. My name's not Steve!\\
''{{Beat}}''\\
'''Patsy''': Okay, but how could I possibly have known that?\\
'''Lorry driver''': Argh, I should have lied about ''Pedro'''s name! I keep doing this! Okay, in you go.
[[/folder]]

[[folder:Video Games]]
* In ''VideoGame/BaldursGate'', there is a quest that involves the player character doing investigations for Aldeth Sashenstar in his offices under the pretense of being his childhood friend. One of his business partners whose behaviour you are there to investigate (and who is himself in fact a doppleganger impostor) asks you whether, if you were Aldeth's childhood friend, you were friends with Dabron as well. Since Dabron is in truth Aldeth's real brother, it's showing ignorance that will give you away at this point, not that it makes a difference for the plot. It's not clear whether this is ''intended'' as a subversion, since the doppleganger could simply be straightforwardly trying to catch you not knowing what it's talking about...
* In ''VideoGame/CallOfDutyBlackOpsColdWar'', this can be avoided during the KGB infiltration mission where Bell and Adler disguise themselves as Soviet soldiers in order to break into a vault and steal a list of sleeper agent names. While making their way to the vault, a young [[spoiler: Imran Zakhaev who is looking for the mole who helped both soldiers infiltrate, enters the elevator they are in and asks them two questions. If Bell answers correctly, Zakhaev exits at the next floor with no problems. But if Bell answers wrong, then the trope gets played straight with Zakhaev attacking both soldiers. During another playthrough of the level, Bell and Alder can avoid answering questions simply by knocking him out.]]
[[/folder]]

[[folder:Web Comics]]
* In ''Webcomic/{{Spinnerette}}'', the real Heather fails one of these because she just can't remember [[https://www.spinnyverse.com/comic/issue-34-17 what she had for breakfast on one particular day a while ago.]]
[[/folder]]

[[folder:Western Animation]]

* ''Manga/{{Naruto}}'':
** Sasuke came up with a very long and convoluted "[[TrustPassword password]]" for his two teammates to memorize in case they ever needed confirmation of one another's identity. Naruto leaves to go to the bathroom, and when he comes back, Sasuke asks him to code in. Naruto repeats it back perfectly... and Sasuke decks the imposter, declaring that the ''real'' Naruto would [[IdiotHero never have been able to remember something that long]].
** Later, the Mizukage does this quite expertly, although her victim is not an impostor, but under control. [[spoiler:Ao, possessed by one of Danzo's men, encounters the Mizukage and Chojuro, apologizing to the latter for getting into a position in which he needed help, then asks the Mizukage to remove the seal on his eye. She then points out that Ao would not apologize to Chojuro, and he'd know the sealing tag could not be removed, then punches him when he [[TooDumbToLive calls her]] [[BerserkButton an old hag]], thus restoring Ao to normal]].
** Naturally, Naruto is [[IdiotHero too stupid]] to pull one of these himself. In one filler arc, he, Hinata and Kiba have to deal with impostors copying their every facet. So naturally when trying to identify the real Hinata, rather than asking a baited question like, "Hey, Hinata, how did you defeat Neji during the Chuunin exams?" he inverts the trope, asking, "What is the name of Hinata's father?" -- a question any good imposter would study beforehand, but one that Naruto himself didn't know the answer to, making it utterly useless even if the imposter didn't know!
** Sakura pulls one of these off [[spoiler:against Zetsu, who was impersonating Neji during the current world war. Or rather, Zetsu does it to ''himself''. When Sakura mentions that Tonton (Tsunade's pig) is being looked at for a twisted leg, [=Zetsu!Neji=] says that it's better to have injured her leg than her hand, then asks if Tonton can still weave signs. Sakura says yes, but then when [=Zetsu!Neji=] comes closer, she pounds him into the ground and tells him that Tonton's a pig.]]
*** This is actually quite a clever application by the writers considering that the Zetsus seem to learn a fair amount about the people they impersonate. Neji's team mate is Tenten. It's not such a stretch to think that Zetsu was simply trying to be too clever.
** Episode 333: The imposter shows up in front of the real Naruto Uzumaki and declares that he is Naruto Uzumaki. Until Naruto said that [[ConfrontingYourImposter he was the real one]] and the imposter got curbstomped.

* Done heartbreakingly in ''Manga/{{Karin}}'' (with a bottle of Tabasco sauce) towards the end of the manga, to determine if the title character's sister has matured to the point where scheduling differences now leave her without any daywalking family. [[OurVampiresAreDifferent Adult vampires]], you see, have no sense of taste.

* Love of ''Anime/FreshPrettyCure'' bluffs an impostor of her mother by switching her and Setsuna's presents and thanking her for the wrong one.
* In ''Anime/DigimonFusion'', episode 39, Kiriha suddenly remembers to return a Digimemory he borrowed from Taiki, and Taiki agrees. Except that the borrowing never happened, and Kiriha hands over a small explosive device that ruins Splashmon's impersonation of Taiki.
* In ''Manga/LoveHina'', Keitaro lies about being a student at Tokyo U, so Naru asks him about the miso-boiled lobster they serve in the cafeteria. Keitaro babbles on for a bit about how it's his favourite food that he can't start the day without, before Naru tells him that there is no such thing as a miso-boiled lobster.

* A rare case of this happening to the protagonist occurs in ''Manga/{{Arisa}}''. Tsubasa is disguised as her titular (comatose) [[TwinSwitch twin sister]] in an attempt to figure out the true identity of "the King", a figure causing all sorts of bullying, manipulation and general chaos at Arisa's school. At one point, she receives a message from someone she strongly suspects to be the King, telling her to meet them at the place Arisa's boyfriend took her on her birthday. Tsubasa can't find that detail in Arisa's letters, so she feigns memory loss from a stay in the hospital to get the boyfriend to tell her. [[spoiler:She was doomed from the start, though, since Arisa's boyfriend ''is'' the King and has known about the switch the entire time.]]

* Both in ''Manga/CaseClosed'' and ''Manga/MagicKaito'' [[note]]Both series take place in the same universe with storylines overlapping[[/note]] has a flashback episode which Kaitou Kid encounters Shinchi Kudo. Kaitou Kid disguised himself as a regular police officer to try and steal the clocktower. The police department know Kaitou Kid is a master of disguise so they ask everyone their name and badge number. When Kaitou Kid is questioned, he gives the person's name and badge number, then the officer ask what their ID number is, which Kaitou Kid gives correctly, and that tips officers that he is Kaitou Kid. Shinichi told the officers to ask for the ID number as most people do not know their ID numbers and figured Kaitou Kid would answer the question.

* In the ''ComicBook/Team7 / ComicBook/{{Weapon X|1991}}'' crossover, the two squads meet in an underground base they were both tasked with blowing up. At gunpoint, they ask each other sports questions to find out if they are Soviets. Amusingly, Wolverine (a Canadian) asks a hockey question, which would probably be more easily answered by a Russian than an American.

* In ''ComicBook/{{Ronin}}'', Peter's suspicions of "Taggart" not being what he seems are confirmed when he doesn't react when Peter claims that his wife Casey accompanied the two on a trip, when she did not. [[spoiler: And when Virgo doesn't react either, he knows she's in on it too.]]

-->'''Past Katie:''' Who was my first boyfriend?
-->'''Future Katie:''' [[ComicBook/FantasticFour Franklin Richards]].
-->'''Past Katie:''' Wrong! It was a trick question. [[GirlsHaveCooties Boys are gross!]]
-->'''Future Katie:''' Give it a few years, honey. You'll change your mind.
-->'''Past Katie:''' Ewww.
* ''ComicBook/BuckDanny'': One story has Buck shot down deep in enemy territory, stuck in a tree in the middle of a swamp. A plane is sent out to rescue him, but the enemy commander can hear their transmissions, and instructs his men accordingly (when Buck shines a light to mark his position for pickup, the soldiers do the same). After the Vietcong show they're listening in by flashing their lights as often as Buck, Sonny tells Buck to use the winning score of the last basketball game played on the Entreprise.
* Visiting the X-Mansion, Banshee starts to sense something is wrong. Seeing Bishop and Gambit, he makes an offhand remark of how "now that the Professor is walking again," he's been busy. When both men agree, Banshee knows they're imposters as Professor X is still in his wheelchair.
* ''ComicBook/WonderWoman1987'': ComicBook/WonderWoman and ComicBook/CaptainAtom are out to rescue ComicBook/SteveTrevor from shape-shifting Durlans. They're separated and "Atom" comes to Diana to say he found Trevor. Suspicious, Diana asks if he also found Captain Nate Adam." When "Atom" says he did, Diana knows this is a Durlan...as Nate Adam ''is'' Captain Atom.

* In ''ComicBook/OldManLogan'' #25, Logan stops at a diner he frequents. He notices the staff is different, and asks the waitress what happened to Lexi. After the waitress responds by saying Lexi took the day off, Logan grabs her and reveals nobody named Lexi has ever worked there. It's then revealed that the real staff has been [[KillAndReplace killed and replaced]] by members of the [[ComicBook/TheIncredibleHulk Hulk Gang]].
* In ''ComicBook/InfiniteFrontier'', DEO agent Cameron Chase confronts a returning Captain Atom on working with the DEO. Atom refuses as Chase brings up their past working together and Atom says he remembers it well but they've both changed since then.
-->'''Chase''': Yeah, but that's the thing...''(raises her gun)'' You and I have never met before.
-->'''"Atom"''': Dammit. Oldest trick in the book.

* ''Film/Terminator2JudgmentDay'': The T-800 asks John Connor's foster mother a question about John's dog, but intentionally gives the wrong name to see if she's actually the shapeshifting T-1000, knowing that if is Janelle, she'll give the correct name. "Janelle" doesn't react to his getting the dog's name wrong, thus confirming it's the T-1000. In the extended deleted scene, as the T-1000 leaves the house, it kills the dog and grabs a bloody dog collar, seeing the name on it and realizing that its target knows that it's there and will be avoiding the house.
* In ''Film/LiveFreeOrDieHard'', John [=McClane=] mentions a police code to Thomas Gabriel's mistress, who is pretending to be a police dispatcher. She says that the police had to dispatch all units in regards to the code. [=McClane=] coolly responds, "Dispatch all units for the naked people running around?"

* From ''Film/{{Dave}}'', where Dave has ben hired to stand in for the President after a stroke renders him comatose.

* This trope shows up in yet another 90s action flick starring Ah-nuld, ''Film/{{Eraser}}'', when Lee Cullen, the witness John Krueger (Arnold) is assigned to protect, gets picked up by an enemy agent posing as John's ally (when John was betrayed and on the run). Remembering John's advice to her to "trust no one" and that [[IWorkAlone John only works alone]], Lee then asks the fake agent to perform John's SecretHandshake, before shooting the imposter in the kneecap and running. Cue a bunch of mercenaries showing up and pursuing her.

* In ''Film/TheSpiderwickChronicles'' movie, the main character's father seems to appear and he (the kid) asks his dad what it was he wanted to tell him. [[spoiler:He's actually the villain, and the kid finds this out because his father was supposed to tell him they (the parents) were getting a divorce.]]
* Used in ''Film/TheReturnOfThePinkPanther'':
-->'''Clouseau:''' What is your code name?\\
'''Dreyfus:''' I don't have a code name! I never had a code name, lunatic!\\
'''Clouseau:''' I understand sir, but you see, only the real Inspector Dreyfus would know he did not have a code name.

* In ''Film/{{Captain Marvel|2019}}'', after Nick Fury's boss calls him "Nicholas",[[note]]Fury having mentioned earlier that no one ever uses his first name[[/note]] Fury realises he's been replaced by a Skrull. He confirms it by claiming their current situation is "just like our mission in Havana",[[note]]which never happened, Fury having also mentioned that he only did missions in cities starting with the letter "B"[[/note]] to which the Skrull agrees. [[spoiler:Gets a CallBack later on when the same Skrull, now an ally and disguised as a Kree guard, uses the same line to let Fury know who he is.]]
* In ''Film/AmericanPsycho'':
-->'''Lady:''' Did you see the ad in the ''Times''?\\
'''Patrick:''' Uh, yeah.\\
'''Lady:''' There was no ad in the ''Times''.

* In ''Film/TheNegotiator'', Chris Sabian is trying to talk down negotiator-turned-hostage-taker Danny Roman. When Roman demands to talk to a confidential informant that can't be located, Sabian reasons that Roman doesn't know the guy either. He substitutes an impostor but is caught when Roman slips in a reference to the impostor's time playing ball for Colorado State and the impostor fails to challenge it despite having Arizona State in his personnel file.
* ''Film/EyesWideShut'': This is how Bill is called out during the orgy sequence. He's asked for the house password in addition to the admittance password, which he says he forgot. Later on, he's told that there was no house password.

* In ''Film/AloneWithHer'', when the protagonist, the girl he's secretly spying on/manipulating, and her best friend are having lunch, the best friend asks him if he'd been to a particular fashion district in Seattle (since he claims to be from Seattle). He says yes, and once he's out of the room, the best friend reveals that she made the fashion district up.
* In the Creator/JetLi film ''Film/BlackMask'' one of the SuperSoldier villains has infiltrated the police and gotten into the unit led by Li's best friend. Late in the movie Li's friend begins to notice the suspicious behavior from the infiltrator, and begins casually asking the infiltrator a few questions, like how long he's been on the force (about a year) and which department he was in before transferring into this unit. In response to these answers, Li's friends says that means the guy must have served with Captain Chan, and talks about how nice a guy Chan is. When the infiltrator agrees with this he's immediately shot: "Chan died four years ago, and he was a real prick!"
* In ''Film/ThereWillBeBlood'', Plainview recalls events in his hometown to test whether his half-brother really is who he says he is.
* ''Film/{{Stalag 17}}'': TheMole tips off suspicious cabinmates by mentioning that he was eating dinner when the attack on Pearl Harbor occurred. While it was noon in the Eastern time zone when the attack happened, it was dinnertime in Germany.
* Variation in ''Film/MenInBlack'': Agent K exposes an alien posting as a Mexican immigrant by saying insulting and threatening things in Spanish, but in a cheery tone of voice, to see if he reacted appropriately.
* In the Creator/GeneHackman film ''Film/NarrowMargin'', Hackman's character tells a pair of "RCMP officers" that he might have the guys who've been pursuing him and his witness all over a train "on a 374". They agree, which tips him off to their being fake. 374 is "indecent exposure".

* In ''Film/DiamondsAreForever'', Mr. Wint and Mr. Kidd [[RoomDisservice pretend to be room service]] and serve Bond and Tiffany diner. After they serve the drinks, Bond remarks he would have liked to drink a claret. Mr. Wint apologizes and says they ran out, then Bond points out the drink they served ''was'' a claret.
* In ''Film/{{Midnight 1939}}'', when Eve poses an an Hungarian royal blood, Georges is onto her and asks if the Budapest subway has been finished yet. She replies that the streets are still torn up. However, as George later reveals, the metro was already finished 50 years ago.
* In ''Film/GodzillaFinalWars'', to prove Daigo is an imposter, Anna presents what is apparently Daigo's dog Clint. "Daigo" cannot guess the dog's name, and eventually, Anna reveals it wasn't Clint at all, but her own dog Candy.
* Major Marquis Warren and Bob the Mexican go back-and-forth with each other throughout the first half of ''Film/TheHatefulEight''. Warren takes an instant dislike to Bob and doubts his claim that Minnie is visiting her mother and left Bob in charge while she's gone. Eventually Warren stops pressing the point because Bob manages to correctly respond to the traps that Warren lays out to catch him (The first one being able to identify the type of tobacco Minnie smokes) [[spoiler:It turns out that Bob ''is'' lying, and had helped kill Minnie before Warren arrived. He was able to dodge Warren's questions because he heard Minnie talk a bit before the rest of the gang killed her, but he still gets shot, because Minnie was notoriously racist towards Mexicans and would not let Bob in if she knew who he really is]].
* In ''Film/FaceOff'', FBI agent Sean Archer infiltrates prison perfectly disguised as his arch-nemesis, Castor Troy, in an attempt to discover the location of a bomb from Castor's brother, Pollux. Ever paranoid, Pollux quizzes Archer on what medication he takes, but Archer is so obsessed with Castor that he is able to answer correctly.
* ''Film/JurassicParkIII'': Paul Kirby brags that he has climbed Mount K2. Billy Brennan exposes him by asking if he made base camp at 25,000 or 30,000 feet. Paul says 30,000 feet, unaware the mountain is 28,251 feet tall.

* ''Literature/HardyBoys'': In the Super Mystery "Stage Fright" the brothers are on the receiving end of this from a suspicious theater employee.
--> '''Damien:''' So what shows have you done?
--> '''Joe:''' Uhh. ''Theatre/ByeByeBirdie''. ''Theatre/TheMusicMan'', you know, the usual.
--> '''Damien:''' So you guys are big [[Creator/StephenSondheim Sondheim]] fans? Me too.
--> '''Joe:''' We love him. Now if you don't mind, I have to-
--> '''Damien:''' That's funny. Because none of those shows are by Sondheim.

--> '''Tom:''' Mandy, tell me what color bathing suit you wore on our date last Friday.
--> '''Mandy:''' Tom, what are you talking about? Nobody wears a bathing suit to the movies, not even in California!

* In Creator/KerryGreenwood's "Raisins and Almonds", Phryne Fisher discovers that a man who has gone to great lengths to masquerade as a Jew is not actually Jewish by the fact that he cannot sing the lullaby "Rozhinkes mit Mandlen" ("Raisins and Almonds"). However, this would not have worked in real life. The lullaby is written in Yiddish, a language based on Middle High German spoken by central and Eastern European Jews. The group of Jews involved in the story were from a community where their Judaic language would have been Ladino, an entirely different language based on Spanish.

-->'''Atom''': Dammit. TheOldestTrickInTheBook.

* In ''Literature/TheLongGoodbye'', when a woman is giving a confession that Marlowe doubts, she talks of dumping a man's body in a reservoir and Marlowe asks her how she got it over the fence. She blusters about adrenaline and then Marlowe reveals that there is no fence. After she breaks down he admits that he's never been there and really doesn't know about fence or no fence. He just thought she was lying.

* In Creator/KirBulychev's ''Literature/AliceGirlFromTheFuture'' series it happens very often, considering that Alice's ArchEnemy is a shapeshifter. It's taken UpToEleven in ''[[Literature/AMillionAdventures The Jewelry Box of the Pirate's Mother]]'': Alice encounters someone looking like her friend Rrrr, only she had just helped the latter flee, bandaged and bleeding. Pretending to be happy, she reminds the false Rrrr that she had to come to Brastak (his planet) from Earth via another planet (while in reality she flew straight there from the planet Penelope), tells him that on Earth it's raining mushrooms, and asks him if he remembers how they met on Pataliputra and played in the snow (that planet has tropical climate even in the polar regions). When he doesn't react to any of it, she is left with no doubt that it's an impostor. Subverted, since she gets carried away so much with thinking up absurdities, the impostor also realizes she doesn't believe him.

* In ''VideoGame/CallOfDutyBlackOpsColdWar'', this can be avoided during the KGB infiltration mission where Bell and Adler disguise themselves as soviet soilders in order to break into a vault and steal a list of sleeper agent names. While making their way to the vault, a young [[spoiler: Imran Zakhaev who is looking for the mole who helped both soilders infiltrate, enters the elevator they are in and asks them two questions. If Bell answers correctly, Zakhaev exits at the next floor with no problems. But if Bell answers wrong, then the trope gets played straight with Zakhaev attacking both soidlers. During another playthrough of the level, Bell and Alder can avoid answsering questions simply by knocking him out.]]

[[folder:Film]]

* ''Manga/FullmetalAlchemist'': Riza Hawkeye and Roy Mustang are hunting down the shapeshifting Envy and get separated; when they meet up again, they exchange a few words, then start off looking for Envy... until Hawkeye puts her gun to Mustang's head. This leads to a [[MassOhCrap universal "oh crap" from the fanbase]], until...

* On ''Series/Charmed2018'', Michela is at first happy her adoptive mother has dropped by for a visit but suspicious of her behavior. They have a talk as Michela says "I'll always be your little Baa-Baa-Boo" and her mother embraces as if it's an old childhood nickname. Too bad for her Michela made the entire thing up on the spot so knows this is an imposter.