History Main / ImpostorExposingTest

* On ''WesternAnimation/RegularShow'' a shapeshifting otter tries to take Rigby's place and the others can't tell them apart. To try to figure out which one's the real Rigby, they go through a series of tests, all of which they "pass" by failing miserably. It's finally when they ask what Rigby's secret fear is that the one that answers is declared the real Rigby and is given a hug by Mordecai... which outs him as the imposter because the ''real'' Rigby would never hug Mordecai.

* Subverted during ''Manga/YuYuHakusho''. Patches were placed on the protagonists that were originally designed to indicate if the characters were harmed, but doubled as a way to indicate an impostor as only the person who placed them on another could remove them. [[spoiler: It didn't work and they resort to SpotTheImpostor tactics instead.]]

'''Nash:''' Look! I am not this Ernest guy. I just happen to look like him. I switched with him, get it? Would the real Ernest be able to knock out Chuck? Or set a time bomb without it going off in his face?[[ArsonMurderAndJaywalking And look at the floors. Notice how clean they've been lately?]]\\

->''"You see, when a man bleeds, it's just tissue, but blood from one of you Things won't obey when it's attacked. It'll try and survive...crawl away from a hot needle, say."''

* In ''FanFic/IronKissed'', the touch of iron is anathema to Fae, causing them pain and breaking their glamours. For this reason, touching iron is occasionally used by those in the know to prove that they are not Fae. Cat Noir, however, is "Iron Kissed", able to touch iron without being harmed, and abuses this to maintain his cover.

[[folder:Film — Live-Action]]
* ''Film/TheThing1982'': Poking people's blood samples with a hot needle is used to identify the Thing since the Thing's blood will react to try to defend itself when endangered.
** In [[Film/TheThing2011 the prequel,]] they use a different test that can't tell who ''is'' a Thing but can ascertain who ''isn't'': [[spoiler:it can't replicate inorganics. Like dental fillings, for instance. If you have cavities...]]

* In the first ''Film/{{Screamers}}'' movie, the protagonist cuts a female soldier to ensure she's not one of the increasingly advanced killer robots. [[spoiler:Turns out the latest models can bleed too.]]
* Averted in this hilarious exchange from ''Film/XMen1'':

'''Cyclops:''' ''[ready to shoot]'' Prove it.\\

''[beat]''\\

* In the ''Film/TheTerminator'', one reason Kyle Reese literally [[PetTheDog pets the dog]] is because dogs can detect Terminators (by furiously barking their heads off). In the robot-dominated future, resistance members have at least one dog hanging around the entrance of their bases to administer this test on all who enter.
** In the sequel, the Terminator calls John Connor's home to see if the T-1000 was there. Noticing John's dog was barking its head off in the background, the Terminator asks if the dog was okay, [[BluffTheImpostor referring to the dog by an incorrect name.]] The T-1000 doesn't realize this was a fluke and exposes itself.
* ''Film/TheWorldsEnd'': To prove that they haven't been replaced by [[ReplicantSnatching "blanks",]] the characters decide to show each other the scars, tattoos, corrective surgeries, or other modifications they got over the years. Gary refuses to do so [[spoiler:because they'd see he'd attempted suicide,]] but instead bashes his head several times against a support beam, showing he's not MadeOfPlasticine and doesn't bleed blue ink.
* In the final scene of ''[[Film/PoliceAcademy Police Academy 6: City Under Siege,]]'' the heroes are in the same room with Commissioner Hurst and the BigBad, who is disguised as Hurst. Their test to reveal the imposter is called "the Pinocchio test", and is rather simple. (They perform a nose pull on both commissioners, revealing the imposter to be wearing a rubber mask).
* ''{{Film/Ronin}}'': Sam tests some of the hired mercenaries in subtle ways. But the defining moment was when he exposed Spence, who claims to be part of the British SAS, as a fraud by calling him out not only on his tactics to take out the group's target but asking him a question that shouldn't have flustered a real SAS soldier. [[spoiler: Notably, after the fraud has left, someone asks Sam the same question he was asking Spence; Sam shrugs it off with "How the f*** would I know?" Given that all SAS recruits are trained in resisting much harsher interrogation than repeated questioning, it doesn't matter that Sam didn't know the right answer to his own question, only that Spence couldn't keep his cool well enough to even attempt a bluff.]]
* ''[[Film/TheAssignment1997 The Assignment]]'' (1997). The plot involves Annibal Ramirez, who bears an [[IdenticalStranger uncanny resemblance]] to the terrorist Carlos the Jackal, being recruited by the CIA to impersonate Carlos. A terrorist who knows the real Carlos is surprised to see him at the duty-free counter at Heathrow Airport because he left Carlos back in Libya.
-->'''Terrorist:''' ''(quietly)'' What are you doing here?
-->'''Annibal:''' ''(winging it)'' [[MathematiciansAnswer Buying cigarettes.]] What are you doing here?
-->'''Terrorist:''' ''(politely)'' Excuse me, sir, I only wanted to know [[TrustPassword where I can get a newspaper?]]
-->'''Annibal:''' [[DramaticallyMissingThePoint Libya, quite a tragedy.]] ''(leaning close)'' I told you never to address me in public. Over by the phone booth and wait; I'll come to you. ''(goes to leave)''
-->'''Terrorist:''' Excuse me, sir. ''(jams carry bag concealing a gun into Annibal's ribs)'' [[PunctuatedForEmphasis I asked, if you knew, where I can get a newspaper.]] ''(OhCrap look on Annibal's face)'' You make the slightest move, and I shoot. And I don't miss.

--> '''Nash:''' That's it. Is everyone who works here a moron? Can't you see what I'm doing? I'm robbing the bank. I'm gonna blow the safe, take the money, and leave. I'm robbing the bank. I'm stealing the money you are paid to protect. I'm robbing the bank.
--> '''Chuck:''' (Just starts laughing)
--> '''Charlotte:''' Look, I don't know what's gotten into you but you can't go through with this! Ernest! Ernest!!!
--> '''Nash:''' Look! I am not this Ernest guy. I just happen to look like him. I switched with him, get it? Would the real Ernest be able to knock out Chuck? Or set a time bomb without it going off in his face? [[ArsonMurderAndJaywalking And look at the floors. Notice how clean they've been lately?]]
--> '''Charlotte:''' You ''ARE'' an impostor!
* In the 1952 film ''Film/InvasionUSA1952'', about [[ExactlyWhatItSaysOnTheTin a Soviet invasion of the USA]], Soviet infiltration units disguise themselves as American soldiers in order to get close to the White House. They claim to be from a Chicago unit, and they speak pretty good English, but they don't know nearly enough about American culture to fool the guards.

* In ''[[https://archiveofourown.org/works/34346623/chapters/98283696#workskin Hawkmoth Gets a Reference]]'', [[UncannyFamilyResemblance Felix]] had disguised himself as his cousin Adrien and sent out an insulting message to the latter's friends. Adrien's friends [[OutOfCharacter realize that "Adrien" is an imposter because of this behavior, especially since he called Marinette a bitch]], and all of them sans Marinette get Akumatized into the monstrous Revealer to hunt him down. When Revealer finds that Adrien and Felix still look like each other, they play back the clip of Felix insulting Marinette, relying on Adrien getting enraged on Marinette's behalf and Felix's shock that Adrien is dating Marinette to figure out who is who.

** In the sequel, the Terminator calls John Conner's home to see if the T-1000 was there. Noticing John's dog was barking its head off in the background, the Terminator asks if the dog was okay, [[BluffTheImpostor referring to the dog by an incorrect name.]] The T-1000 doesn't realize this was a fluke and exposes itself.

* In ''VideoGame/FinalFantasyXIV'', Themis and the [[PlayerCharacter Warrior of Light]] encounter Hephaistos, who is claiming to be [[spoiler: Lahabrea]]. He answers with Themis, which confirms the boy's suspicion that Hephaistos is not who he claims he is. Themis later states that the real person would have answered with [[spoiler: Elidibus]], which is his true name.

* The 1996 TVB adaptation of ''Literature/JourneyToTheWest'' has a chapter where an absurdly powerful Centipede Demon takes on the form of Sanzang, resulting in having two identical Sanzangs much to the confusion of his disciples, Wukong, Bajie and Wujing. After Wukong's X-Ray visions failed to expose the fake Sanzang from the real one (a trick which worked 99 out of 100 times in the past - the Centipede Demon is just ''that good'' of a shapeshifter) the trio decides to quiz the two Sanzangs on their past adventures, leading to a nice ContinuityCavalcade that {{Call Back}}s on the previous chapters, with questions like, "Who is my (Wukong) brother-in-arms in my training days?" [[note]] '''Answer''': The Bull Demon. [[/note]] "Where did we first met when I (Bajie) pretended to be a rich nobleman?" [[note]] '''Answer''': The Ko's Residence [[/note]] "What did you write in the palm of my (Wujing) hands in the bottom of the River of Sands?" [[note]] '''Answer''': The word "Buddha" [[/note]] "Who defeated me (Wukong) in battle and reverted me back to monkey form?" [[note]] '''Answer''': The Red Boy [[/note]] "In which country did I (Bajie) become a prince?" [[note]] '''Answer''': The Kingdom of the Sacred Elephant [[/note]] "What is my (Wujing) occupation in my previous life, a hundred years ago, before my exile from heaven?" [[note]] '''Answer''': The Jade General [[/note]] … to the horror of Wukong, Bajie and Wujing, BOTH Sanzangs answered all twenty or so of their questions ''correctly'', making them realize the Centipede Demon is likely a mind reader and far more powerful enemy than they've previously faced.

If the impostor is an alien, they can cut themselves and see who has AlienBlood. If it's a vampire, they can dip their hands in holy water and see who gets burned.

* During Ganon's attempt to replace Zelda with an EvilTwin in ''WesternAnimation/TheLegendOfZelda'', Link deduces early on that he's with an imposter Zelda due to [[TheMirrorShowsYourTrueSelf her lacking any reflection when they pass by a body of water]] and plays along with her as he finds a way to tell the real one apart when they confront her. Upon learning that the imposter is willing to make the moves on him, he eventually decides that best way to tell apart the two Zeldas is through a kissing contest, as he knows the real one [[UnresolvedSexualTension would reject to giving Link a kiss]].

* In ''[[Fanfic/{{Eleutherophobia}} Escape from L.A.]]'', Eva makes Tom drink instant maple and ginger oatmeal when they reunite at the church shelter to make sure he hasn't been reinfested since she last saw him.

* In ''ComicBook/HowlingCommandos'', Fury is suspicious that one of the "prisoners" in a camp escape is a German spy. After a long hike, he has Howler Gabe take a long sip from a thermos of water and then offer it to the rest. Sure enough, the Nazi is the one who, despite obvious thirst, refuses to drink from the same thermos a black man just used.

** When Sam and Dean meet their long-lost half-brother Adam, Deans puts him through a battery of tests, all of which he passes [[spoiler: because it's actually a ghoul who killed and ate Adam and there's no test for that.]]

** In the sequel, the Terminator calls John Conner's home to see if the T-1000 was there. Noticing John's dog was barking its head off in the background, the Terminator asks if the dog was okay, referring to the dog by an incorrect name. The T-1000 doesn't realize this was a fluke and exposes itself.

* ''Series/TheWheelOfTime'': In episode 8 Ba'alzamon places Rand into a scene of a perfect future, where he lives with Egwene and their daughter in Two Rivers. Subversion: Rand asks about things only the real Egwene knows, but she gives answers that match his memories of her. Double subversion: [[spoiler:this perfect Egwene did not [[CareerVersusFamily leave him]] to become Wisdom or Aes Sedai, thus he deduces she's fake]].

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[[quoteright:291:[[WesternAnimation/FraidyCat
https://static.tvtropes.org/pmwiki/pub/images/a044c1f8_1a12_4f29_bfaf_6d586047b0b3.jpeg]]]]

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[[caption-width-right:291:An impostor cat posing as a famous cat and the famous cat are given food. The famous cat turns his nose, and the impostor downs the plate. Problem solved.]]

* The 1996 TVB adaptation of ''Literature/JourneyToTheWest'' has a chapter where an absurdly powerful Centipede Demon takes on the form of Sanzang, resulting in having two identical Sanzangs much to the confusion of his disciples, Wukong, Bajie and Wujing. After Wukong's X-Ray visions failed to expose the fake Sanzang from the real one (a trick which worked 99 out of 100 times in the past - the Centipede Demon is just ''that good'' of a shapeshifter) the trio decides to quiz the two Sanzangs on their past adventures, leading to a nice ContinuityCavalcade that {{Call Back}}s on the previous chapters, with questions like, "Who is my (Wukong) brother-in-arms in my training days?" [[answer]] The Bull Demon. [[/answer]] "Where did we first met when I (Bajie) pretended to be a rich nobleman?" [[answer]] The Ko's Residence [[/answer]] "What did you write in the palm of my (Wujing) hands in the bottom of the River of Sands?" [[answer]] The word "Buddha" [[/answer]] "Who defeated me (Wukong) in battle and reverted me back to monkey form?" [[answer]] The Red Boy [[/answer]] "In which country did I (Bajie) become a prince?" [[answer]] The Kingdom of the Sacred Elephant [[/answer]] ... to the horror of Wukong, Bajie and Wujing, BOTH Sanzangs answered all twenty or so of their questions ''correctly'', making them realize the Centipede Demon is likely a mind reader and far more powerful enemy than they've previously faced.