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[[quoteright:350:[[Manga/DeathNote http://static.tvtropes.org/pmwiki/pub/images/Find_Kira_the_easy_way.jpg]]]]
[[caption-width-right:350:One of the more embarrassing ways to blow your SecretIdentity.]]

->''"Accuse a guy of having bad locks and before you know it, he's telling you where his motion detectors are."''
-->-- ''Series/BurnNotice'', "Breaking and Entering"

Ben is undercover. Stan, typically a [[TheRival rival or enemy]], knows or at least suspects as much; and tests his suspicion by blurting out Ben's real name. Inevitably, Ben will, quite unprofessionally, respond to the use of his name, confirming Stan's suspicions. Note that Ben's reaction is, in and of itself, sufficient to convict him, even if the two are alone and Stan could not possibly be addressing anyone else.

The trope operates independently of the good-bad alignment of either party.

The ploy used to force TheReveal need not be a name; it can be a specific word/phrase, or something spoken in the other character's native language. It can even be a non-verbal prompt, such as a familiar face, location, scent, etc. The point of the trope is that the infiltrator is hiding something about himself, and deceived tricks them into revealing it by acting as if he already knows the truth, thus causing an automatic, unthinking reaction.

One of TheOldestTricksInTheBook.

Subtrope of ReflexiveResponse. See also PullTheThread, OutOfCharacterAlert, BluffingTheMurderer. If deceived wasn't suspicious until infiltrator responded the way they did, it's SomethingOnlyTheyWouldSay. If the deceived says something that only an impostor wouldn't be suspicious of, it's BluffTheImpostor. INeverSaidItWasPoison may occur if the infiltrator mentions some facts about the case that deceived hadn't revealed. SuspiciouslySpecificDenial is ''totally not'' a related way of letting information slip. This also gives Ben a case of ImplausibleDeniability.

Not to be confused with HowDidYouKnowIDidnt, where someone appears to act on certain information that another person knows is secret, then reveals at the end that they didn't know it after all. The {{inverted}} trope is INeverToldYouMyName, when the infiltrator cover that's blown by revealing that they know too much about the deceived.



[[folder:{{Anime}} and {{Manga}}]]
* In an episode of ''[[Anime/YuGiOhFirstAnimeSeries Yu-Gi-Oh!]]'' series 0, a cop announces that a criminal has been tracked to the joint where Yugi and Jonouchi have gone for a burger, and their friends are working. The police sergeant says it might help that the crook is allergic to eggs; Anzu says (falsely) that he will be easy to catch, because the burger buns have lots of egg in them. At that, the crook freaks out and tries to bolt, despite having suffered no ill effects when he ate there the day before. In a subversion, this crook turned out to be a small-time shoplifter; the real perp did not fall for it.
* In ''Manga/DeathNote'', Light Yagami of all people is once tripped up by this ploy, when Namikawa tells him that he already knows that [[spoiler: Higuchi is the Yotsuba Kira]] - it's only a very strong hypothesis at this point, but Light's surprised reaction is all the confirmation he needs. Of course, Light is [[spoiler:an amnesiac at the time]].
-->'''Misa''': Wow, that Namikawa guy is pretty smart!
-->'''L''': No, Light just messed up.
** At the end of the series, Light does this again. [[spoiler: "Looks like I win, Near." You'd think he'd wait until they were actually dead to start gloating. Dying doesn't make someone ''deaf'', Light.]] Considering some of them were [[TakingYouWithMe armed]], Light was very nearly TooDumbToLive.
* Even Lelouch, TheChessmaster of ''Anime/CodeGeass'' is not immune to these.
-->'''Rivalz''': [Lelouch]'s even holding a household account book...
-->'''Lelouch''': How do you know about that?
-->'''Rivalz''': Huh, you really do?
* ''Manga/DetectiveConan'' used this early on, when Ran suspects (correctly) that Conan is really Shinichi, so she tests it by seeing how he responds when called by his real name. It works, and he falls for it again when she mentions one of their teachers, [[StatusQuoIsGod but he manages to throw her off anyway.]]
* The Novelization adds one of these to ''Anime/MobileSuitGundamSEED''. In the original series, when watching Kira fight, Andy quickly deduces that the Strike Gundam's pilot is a Coordinator. He later figures out that Kira is the pilot, most likely by watching his actions during a Blue Cosmos terrorist attack both are caught in. Realizing Kira is a both a Coordinator and not a native, and puts two and two together. He then confronts Kira in a scene which is played like he flat out ''knows'' what he is saying is true. In the novel, he suspects it (bases on his observations), but isn't quite sure, and uses one of these to confirm it.
* This is how Videl figured out that Gohan was Saiyaman in the ''Anime/DragonBallZ'' manga.
-->'''Videl:''' So [[SecretIdentity your identity is a secret]], right?
-->'''Saiyaman:''' Uh, yeah. That's correct...
-->'''Videl:''' So, Gohan, how'd you get out of school?
-->'''Saiyaman:''' Simple! I just said I was going to the bathroom and got here as... ''crap''.
* Used ''heroically'' in ''Manga/MahouSenseiNegima''. The WildCard Kurt just finished a HannibalLecture, and made a sort of WeCanRuleTogether speech about saving "everyone," all 92 million of them--Negi then makes an educated, but still wild guess about what the disaster is, and Kurt, shocked, accidentally confirms it--and Negi points out that this confirmation has let loose the minor detail that Kurt's great plan for salvation is planning on abandoning 17/18ths of the planet.
* Used by Maru in ''Otona Keikenchi'' towards Seiji so he can learn more about his relationship with Yumeji and tease him relentlessly about it.
* Not quite sure ''how'', but in ''Manga/BirdyTheMighty'', Birdy says the [[http://www.mangafox.com/manga/birdy_the_mighty_ii/v02/c021/4.html trope]] line.
* ''Manga/FullmetalAlchemist'':
** Riza pulls this on Envy:
-->'''Envy-as-Roy:''' ''(being held at gunpoint)'' Lieutenant, what's the meaning of this?
-->'''Riza:''' When we're alone, the Colonel always calls me "Riza".
-->'''Envy:''' ''Shit!'' You two are--
-->'''Riza:''' Just kidding. Thanks for blowing your cover.
** When Ling is unsure if he's talking to the real Ed, or Envy is disguise, he dismissively calls him a pipsqueak. [[ReflexiveResponse Ed responds as]] [[BerserkButton one would expect.]]
* In ''VisualNovel/OtomeWaBokuNiKoishiteru'', Sion started suspecting that Mizuho might be WholesomeCrossdresser pretty quickly, but she only confirmed it when - while passing Mizuho in the bathroom - she casually said "Your fly's undone." In Mizuho's defense, 'she' had only been acting like a girl for a few days by then. Later on, she gets so good at it that Sion actually forgets that 'she' is a boy sometimes...
* When trying to determine if a cruise ship stowaway is actually one of Dio's lackeys in part III of ''Manga/JoJosBizarreAdventure'', Jotaro claims that he can tell the difference between Stand users and normal people by the fact that the blood vessels on their nose pop when they smell smoke. All of Jotaro's comrades instinctively move to touch their nose - as does the supposedly {{Muggle}} ship captain, exposing him as the a Stand user and TheMole.
* In ''Anime/SailorMoon R'', Esmeraude launches a plan to infect people with dark energy using a flu virus. Minako and Chibiusa go to the pharmacy to pick up medicine for the Tsukinos, and coincidentally encounter Esmeraude, who seizes the opportunity to try and kidnap Chibiusa while she's at it. Minako/Sailor Venus comes to the rescue, prompting the following exchange:
--> '''Esmeraude:''' I see! You somehow used your power to locate our Dark Henge site.
--> '''Sailor Venus:''' Sure did!
--> '''Esmeraude:''' Damn! So, to be clear, you're saying you knew about our plan to make the entire city sick by spreading medicine laced with dark power from this hospital base?
--> '''Sailor Venus:''' Yeah! It was so obvious!
--> '''Chibiusa:''' Wow, Venus will say anything based on the situation.

[[folder:Comic Books]]
* In ''{{ComicBook/Asterix}}'', a Goth-Gaul interpreter pretends not to speak Gaul to prevent Astérix from interrogating him. Later on he sneezes and when Astérix absent-mindedly says "Bless you" he thanks him, ''in Gaul''. Made funnier by his subsequent frantic insistence that he does not speak Gaul - still in Gaul.
* ''ComicBook/LuckyLuke.'' The cowboys have captured a Native American and try to question him, but the prisoner apparently does not speak English. Lucky Luke serves him a glass of whiskey and asks him if he'd like some rocks on it. "No, thank you," answered the soon-to-be official interpreter.
* Subverted in ''ComicStrip/KnightsOfTheDinnerTable'': Brian's opponent in a naval wargame tries this, prompting Brian to "confirm" it by bursting out "How did you know that was my plan?." At the climax of the game, it is revealed that Brian had a different plan all along, and ''deliberately'' did this to mislead his opponent.
* In ''ComicBook/TheWalkingDead'', while the Governor already suspected [[spoiler: suspected Rick's group was in a prison,]] he could not confirm it. Instead, he informed Rick that he had [[spoiler: released Glenn (he hadn't) after he admitted (he didn't) they were indeed seeking shelter in the prison.]] It was the look on Rick's face that confirmed his suspicions.
* A complex variant in ''ComicBook/{{Watchmen}}'': Doctor Manhattan can "remember" events happening in his future. It's immensely confusing for others to be told by him that "we will go to X, and there you will tell me about Y", and later, when the other casually mentions Y, Manhattan is startled, because they've just reached the point in time when he learns about this. You Just Told Me indeed.
* In the first volume of ''Rabbit and Bear Paws'', Bear blows his cover by excitedly shouting when his mother mentions the possible reward of maple candy.

[[folder:Comic Strips]]
* ''ComicStrip/{{Doonesbury}}'' for [[http://assets.amuniversal.com/88e046c00b560130fb37001dd8b71c47 November 17th, 2012]]. Zipper starts a rumor that Walden College was going private. He approaches the president of the college and tells him that he started the rumor, and the president asks him how he knew that they were planning to do just that. Zipper says "I didn't until just now. I can't believe that worked, I saw it on some cop show".

* In ''[[http://archiveofourown.org/works/2062614/chapters/4483347 Hermione's Furry Little Problem]]'' Fred and George tease Harry about his and Hermione's relationship.
-->'''Harry''': Look, Hermione's just a friend...\\
'''Fred''': Whose bed you sleep in?\\
'''Harry''': How did you know that?\\
'''Fred''': I didn't, but I do now.
* ''[[https://www.fanfiction.net/s/11191235/25/Harry-Potter-and-the-Prince-of-Slytherin Harry Potter and the Prince of Slytherin]]'':
-->'''Harry:''' So, Hagrid's breeding dragons, I take it?\\
'''Hermione:''' How did ''you'' know that?\\
'''Harry:''' I didn't. I guessed and you just confirmed it.
* In ''Fanfic/ThousandShinji'': When [[spoiler:Kaworu]] shows up, he gives away [[HumanoidAbomination his true nature]] to Shinji by [[spoiler:referring to humanity as "Lilim"]].
* In ''Fanfic/TheStalkingZukoSeries'', When Katara asks Mai about how she resolved her disputes with Zuko, Mai says that her preferred method- the silent treatment- is unsuitable for Katara. Katara asks how Mai knew that she and Zuko were an item, and Mai quotes the trope verbatim.

* In ''Film/{{The Avengers|2012}}'', Black Widow is being interrogated by a corrupt Russian general. When Coulson calls her to come in, she [[ObfuscatingStupidity breaks character]] and protests that "this guy is giving [her] everything," to the hapless general's confusion and dismay.
* Famously used in ''Film/TheGreatEscape'' when a couple of prisoners stop at the border. Everything is going well until one of the guards wishes them "good luck" in English, causing one of the prisoners to respond, "Thanks!" revealing himself as British. In real life, this was precisely how the leader and companion were caught. The trope is averted later in that film when another German attempts this on one of the escapees. He bluntly confronts the escapee with, "You are American!" but the escapee continues to feign ignorance and the German leaves. [[spoiler: [[TearJerker But he gets caught anyway when the German comes back]]]]
* Gene Simmons attempts this tactic against John Stamos in the movie ''Film/NeverTooYoungToDie''. In a subversion, Stamos manages to bluff his way out of the situation, though not convincingly:
-->'''Ragnar:''' Stargrove!
-->'''Lance:''' Is that name supposed to mean something?
-->'''Ragnar:''' My mistake.
* In ''Film/DieAnotherDay'', Bond uses this method to reveal the identity of Gustav Graves/Colonel Moon. The trope as played out here is somewhat less than effective, since the audience has already been alerted to this plot point.
* In the Bond-wannabe film ''Film/AgentForHARM'', the lead character exposes the ersatz Bond girl as a villainous double agent by using her real name. The "even though they are alone in the room" clause, as stated above, applies here.
* In ''Film/SupermanII'', Lois tries this to reveal Clark's secret identity, first by calling him "Superman" and then by jumping into Niagara Falls. Naturally, Clark manages to rescue her without being obvious. In the restored cut, she tries jumping out a window, with the same result. Then she tries shooting him with a blank. Clark doesn't know that it's a blank, however, so he fesses up to being Superman.
* Straightforward example in ''Film/WhoIsCletisTout'' Sloppy work on Finch's part to respond to his name, considering he was a fugitive in the middle of a room of cops.
* In the ''Film/SgtBilko'' movie, Bilko's soldiers [[FeedTheMole give Thorn's goons false information]], making him remove a 'key component' of the Hover Tank so it wouldn't work at the demonstration the next day. After Bilko and his troops make it so the tank appears to work, Thorn confronts the General overseeing the demonstration, insisting that Bilko is incompetent and that they faked the whole thing. When asked for proof, he reveals the component he removed... showing the four star General and the crowd of witnesses that he deliberately sabotaged the project out of spite towards Bilko.
* In the 1993 adaptation of ''Film/TheFugitive'', U.S. Marshal Sam Gerard (Creator/TommyLeeJones) tricks fugitive surgeon Dr. Richard Kimble (Creator/HarrisonFord) into revealing himself when Gerard calls [[StairwellChase down a stairwell to a retreating figure]], "RICHARD!" Kimble involuntarily looks up, giving himself away.
** In the original script, Kimble ''doesn't'' look up when Gerard calls to him, even though other people in the stairway do. However, he does freeze in place for a moment (no doubt stopping himself from [[ReflexiveResponse reacting]] to the sound of his name), before continuing down the stairs at a visibly faster pace than before. The deliberate lack of response tips Gerard off just the same.
* Exaggerated in ''Film/SpiesLikeUs'' when Agent Millbarge suspects that a pair of agents supposedly sent to help him and his partner are actually KGB agents. He tells them a joke in Russian, causing them both to explode in laughter, saying "Da! Da!"
* ''Film/AustinPowersInternationalManOfMystery''
-->'''Austin Powers''': Your boss, Number 2. I understand that cat's involved in big underground drills.
-->'''Alotta Fagina''': How did you know?
-->'''Austin Powers''': I didn't, baby. You just told me.
** In this case Austin was aware of the fact ahead of time and was invoking this trope purely to look classy.
* In ''Film/LegallyBlonde'', a lawyer outs a witness as gay ([[NoBisexuals to prove he couldn't have been the female defendant's lover]]), by asking him several rapid-fire innocuous questions (like "How long have you worked for her?" etc.), ending with "And your boyfriend's name is?" which the witness answers "Chuck" without thinking. When the attempts to reestablish cover by claiming that he was confused by the rapid-fire way in which the questions were asked, and that Chuck is only a friend rather than his boyfriend, Chuck himself stands up and takes very vocal offense, leaving the witness's credibility utterly shot.
* In ''Film/MrAndMrsSmith2005'', John, already suspicious about his wife, "accidentally" drops an open bottle of wine that she catches perfectly; then she realizes his ruse and lets it spill.
* As with the above example, ''Film/CrouchingTigerHiddenDragon'' also uses this tactic. Shu Lien suspects Jen is the thief who stole the Green Destiny sword, and confirms it by purposefully dropping a full cup of tea, which Jen catches effortlessly without spilling a drop.
* In ''Film/BillyJack'', Billy uses this ruse to trick Jean Roberts into revealing that she was raped by Bernard Posner.
* ''Film/FatalInstinct''. Ned Ravine's secretary Laura Lincolnberry tells him that he has lipstick on his collar. He looks at his collar and says he doesn't. She says "You just told me" (if he hadn't been fooling around, he wouldn't have had to look at his collar).
* Used in ''Film/MenInBlack'', where Agent K finds out which of a number of illegal Mexican immigrants is actually an alien because he cannot speak a word of Spanish.
* In ''Film/AllThePresidentsMen'', Woodward and Bernstein have a document identifying certain individuals only by the first initial of their surname. They believe "P" is a man named Porter, so while questioning a woman who may know, they casually intimate in a brief throwaway aside that they ''know'' "P" to be Porter. Her last words as they leave is an incredulous "How did you know about Porter?"
** The two discuss the plan before they go and do it. Rarely, they discuss what happens if they're wrong. After a beat, they admit if that's the case, "We're screwed."
* In ''Film/QuantumOfSolace'', M calls CIA to ask about a member of Quantum they're investigating. She gets transferred to Gregg Beam, who denies any operations. M then tells her subordinate that this proves the opposite, as there would be no need for the CIA Section Chief for South America to personally get this call otherwise.
* In ''Film/WhereEaglesDare'', Nazi General Kramer is eventually convinced Schmidt is an ally and hands over a list of names of spies working in Britain, as well as confirming the identity of TheMole. Smith immediately reveals he had no evidence for this and the purpose of his mission was to extract the information from the Germans.
* In ''Film/StateOfPlay'', while the reporter Cal is heading up to a crime scene.
-->'''Cal:''' I heard Metro ballistics was just here.
-->'''Detective:''' Who told you that?
-->'''Cal:''' You just did.
* A variation in ''Film/KissOfTheDragon''. The climax involves Creator/JetLi's character storming the French police station full of {{Corrupt Cop}}s. He calls the BigBad (the police chief) and asks him to look out the window. When he does, Jet Li's character tells him that, now that he knows where he is in the building, he's coming up.
* In ''Film/{{Taken}}'', the PapaBear protagonist confirms his daughter's Albanian kidnapper's identity by getting a translator to write the phrase "good luck" in Albanian and asking the kidnapper to translate it into English. During the kidnapping, this was all the kidnapper said to him on the phone, so he wanted to confirm the voice.
* Subverted in the climax of ''Film/{{Se7en}}''. When Det. Somerset leaves serial killer John Doe in the custody of Det. Mills to open a suspicious package, he realizes that it contains ''[[spoiler:the head of Mills' wife]]''. All of this happens a considerable distance away from Mills, who is holding Doe at gunpoint to make sure he doesn't run, but Doe blatantly tells Mills what's in the box; for a moment, Mills is too stunned to believe what Doe has said, until Somerset returns begging him to drop the gun. As Mills repeatedly begs Somerset to just tell him what's in the box, Doe simply says, "He just told you," since Somerset's refusal to admit it is proof that Doe is telling the truth.

* Done subtly in ''Discworld/TheFifthElephant''. The Patrician assigns Commander Vimes a manservant, Inigo Skimmer, for his trip to Uberwald. Vimes tosses an orange at him, and it bounces off. He doesn't say anything at that point, but later, when he reveals that he knew about Skimmer being a spy, he points out that a normal person would have either caught the orange or at least flinched (to confirm this theory, he later lobs one at Sergeant Stronginthearm, who ducks); Skimmer looked at it, recognized that it wasn't a threat, and let it go on its way, inadvertently showing that he has had assassin training.
** Played with a bit in ''Discworld/NightWatch'' too. Coates informs Vimes that "I know you're not the real John Keel." Vimes keeps a totally straight face, only to realize that that gave him away more thoroughly than anything he could have said.
*** Although in that case Coates didn't even need the confirmation, as he ''did'' actually know for a fact that Vimes wasn't the real Keel [[spoiler:because Keel had been Coates' own mentor in the past]].
*** Also done at the end of the book, when Vetinari calls Commander Samuel Vimes [[spoiler:Sergeant, and Vimes replies instantly. Vimes accuses Vetinari of having known all along, and is told "Not until, oh, one second ago."]]
* In Creator/IsaacAsimov's mystery novel ''A Whiff Of Death'', the killer gives himself away by reacting to the detective grasping and starting to turn a valve that had been rigged to cause an explosion (the trap had previously been detected and neutralized).
** In one of Asimov's short mystery stories, the culprit is a Québécois person using a false identity of an American. The detective tricks him into revealing his true identity by asking him to write the word "Montréal," and he writes it with an ''accent aigu'' on the e, whereas someone who only spoke English wouldn't spell it that way.
** Another story involves the classic thrown object, with the twist that the perp is the ''thrower''. He gives himself away as having spent a long time on the moon when he throws it ''far'' too short in normal gravity.
** In a third Asimov story, "I'm In Marsport Without Hilda," a detective is trying to figure out which of several people in a room is a drug smuggler. All of the innocent suspects are currently [[MushroomSamba loopy]] and speaking stream-of-consciousness gibberish, because they were given a drug to prevent space sickness, and the guilty party is faking it. Unable to figure out who is guilty, the detective, out of frustration, starts telling them about the hot date he would have had, if he wasn't stuck interviewing them. The guilty party's, um, "reaction", gives him away.
** In ''Literature/TheRobotsOfDawn'', Baley has circumstantial evidence that a person was communicating with a unique robot for reverse-engineering purposes. The person is, unfortunately, a very respected member of society (and on on another planet at that), so his word carries more weight than his. So, after presenting the evidence, he says the man might have committed the very crime he accuses his opponent of as a side effect. The criminal blurts that couldn't have been caused by his experiments... mind you, that other crime is considerably lighter, mere destruction of property, so the criminal is forced to fold on the spot.
** Asimov must absolutely love this trope, because he uses it again in one of the stories in "I, Robot," when a scientist interviews a politician he believes to be a robot in disguise. When the scientist refuses to name the source who brought the rumors to him, the politician asks if they can just assume it's his political rival and move on. He keeps on using the rival's name for the name of the source in their conversation, until the scientist forgets that he's supposed to be keeping it a secret and uses it himself. The politician, who used to be a lawyer, calls this a "shyster trick."
* This is used a few times in the first book of Terry Goodkind's ''Literature/TheSwordOfTruth'' series.
** And then in the fourth, Kahlan appears to have learned the method - at least where girl talk is concerned.
* In Creator/StephenFry's ''[[Literature/TheLiarNovel The Liar]]'', the main character tries to hide his identity from the police, only to respond to his own name, which they got from the inside cover of a book he had with him. This is based on His Fryness's own experience.
* Happens in ''Literature/{{Animorphs}}''; Cassie (morphed as Rachel) is talking to a [[PuppeteerParasite Controller]], and he suspects her, so he randomly blurts out "Andalite!." If Cassie had reacted, she'd have given herself away, but she plays it cool and responds "[[IncrediblyLamePun Yeah, a light would be good too.]]"
** She does, however, fail spectacularly when Visser One takes her by surprise by accusing her of being human. It turns into a long silence while they frantically figure out how to respond, before eventually deciding that nothing they can say will give them away as totally as that long silence already has.
* ''Literature/{{Dragaera}}'' novels:
** This is the ''modus operandi'' of Vlad and Kiera in ''Literature/{{Orca}}''. They basically spend the whole book going around in various disguises talking to the conspirators, pretending to know more than they do (which is nothing) until they get a reaction, and then put all the pieces together.
** In ''Literature/{{Iorich}}'', the Empress thanks Vlad for his help in exposing a conspiracy in the East (detailed in the previous novel, ''Literature/{{Jhegaala}}''). Vlad asks her how she knew he was the one who sent those anonymous letters, and the Empress replies that she didn't, until now.
* Literature/SherlockHolmes has used it at least once: in ''The Three Gables'', where to get the whole story he sends the villainness a note reading simply, "Shall it be the police, then?" He only has hunches, but by story's end she's told him enough to prosecute (if he wished).
* In ''Literature/{{Wicked}}'', Elphaba pretends not to know Fiyero, and is a good enough actress not to respond to her name... but she does later respond to her childhood nickname, Fabala, while he chases her. It's kind of a moot point, though, as he was already sure it was her.
* Egwene uses this in the [[Literature/TheWheelOfTime Wheel of Time]] book, The Gathering Storm. Black Ajah are the only Aes Sedai who can lie. She knows that a certain Aes Sedai is Black Ajah and needs to prove it to the rest. She asks her a rapid-fire series of questions, to which any Aes Sedai would give vehement denials. ("Do you consort with the Forsaken?" "Do you serve the Dark One?") Then she asks a question about her target's hair color. Her target denies her own hair color, which proves to the assembled audience that she is Black.
** All Aes Sedai are required to swear a magically binding oath to not speak any word that is not true. They literally choke up any time they are about to actually lie. (Though they are masters of [[FromACertainPointOfView distorting and twisting meanings]]).
** Also used by Lady Dyelin to Birgitte. It's implied that this has happened multiple times offscreen as well as the onscreen times. In the onscreen times, Birgitte handles herself well.
* Creator/MarkTwain's ''Literature/AdventuresOfHuckleberryFinn''. While Huck is wearing a dress and pretending to be a girl, a woman determines he's actually a boy by tossing a lump of lead into his lap. He clasps his legs together to catch it, the way a boy wearing pants would do, instead of spreading his legs apart, the way a girl wearing a dress would do it.
* ''Literature/TheWayOfKings'' (first book of ''Literature/TheStormlightArchive''): [[BrokenAce Kaladin]] proves his suspicions that [[TheLancer Teft]] was once a [[SergeantRock squadleader]] using this method.
-->"Teft," Kaladin ordered. "Split them into pairs by size and weight, then run them through an elementary forward spear stance."\\
"Aye, sir!" Teft barked. Then he froze, realizing what he'd given away. The speed at which he'd responded made it obvious that Teft had been a soldier. Teft met Kaladin's eyes and saw that Kaladin knew. The older man scowled, but Kaladin returned a grin. He had a veteran under his command; that was going to make this all a lot easier.
* In ''Literature/StElmosFire'', Alec replies "What did Kevin tell you?" after his girlfriend asks him about his "extracurricular love life" and beats on Kevin in retaliation. Kevin hadn't spilled a thing; his girlfriend just had a hunch.
* 19th-century amateur detective Literature/JulianKestrel uses this in his first novel ''Cut to the Quick''
--> "So," said [[spoiler: Guy, his]] eyes wide but [[spoiler: his]] laughter abating, "I suppose Bliss told you everything."
--> "I haven't spoken to Bliss," said Julian. "Felton couldn't find him. All he found was this." He indicated the patchwork sack.
--> "You mean--that's all you have?" [[spoiler: Guy]] gaped at the sack. Laughter convulsed [[spoiler: him]] again. 'You mean, if I'd only held my tongue-- No, really, this is funny! It's an absolute screamer, don't you see? On the strength of a worm-eaten pedlar's sack, I've put a rope around my neck."
* In the last book of ''Literature/CodexAlera'', Tavi and several members of his high command are on a ship under attack by [[HordeOfAlienLocusts Vord]] scouts. Magnus has been suspicious of [[spoiler:Valiar Marcus]] for several books, since he seems to know a little too much about espionage for a decorated soldier, [[spoiler:and particularly Cursor methods of going about it]]. So, at the very end of the fight, he shouts, "[[spoiler:Fidelias]]! Behind you!," [[spoiler:having narrowed down the list of high-level Cursors he could be to one specific traitor.]] Tavi, who had agreed to the plan thinking it would ''exonerate'' his loyal subordinate, is very, very angry when [[spoiler:Marcus]] immediately whirls around.
* In the first ''Literature/DaughterOfTheLioness'', Aly mentions weapons in hidden storerooms under the stables. Lokeij says he has the stables watched all the time, and there's no way Aly could have known about them. Aly replies "I didn't know until now."
* In ''[[Literature/JediAcademyTrilogy I, Jedi]]'', Corran Horn goes undercover as ''Keiran'' while training at Luke Skywalker's Jedi academy, changing his name since he's a mildly famous pilot. Interestingly, after leaving the academy "Keiran," going by yet another name, is [[BluffTheImpostor questioned about Luke]]. He goes on to display an appalling lack of knowledge about one of the single most famous and important people in the galaxy in order to keep up the ruse.
* In ''[[Literature/TheThrawnTrilogy Dark Force Rising]]'', when Mara Jade, a former assassin for Emperor Palpatine, meets with Grand Admiral Thrawn, he says "Come closer, Mara Jade." (The two had met several years before and she was under an assumed name). She begins instinctively walking forward, catches herself and comments that Thrawn shouldn't have to rely on such cheap tricks to verify who she was. He agrees, and then asks her questions that only she would know the answer to.
** Used again in the same book. No one in the New Republic knows the name of the new Grand Admiral on the scene. Han Solo meets with a ship thief who does know, and is offering to show Han the location of a lost fleet before the Empire finds it.
---> '''Han''': "What makes you think the Empire's involved?"
---> '''Ferrier''': "With Grand Admiral Thrawn in charge over there? He's involved in everything."
---> '''Han''': "Thrawn, huh? Thanks, Ferrier."
* In Zahn's ''Literature/OutboundFlight'', Thrawn is able to get an awful lot of information out of a Corellian guest/prisoner who really doesn't want to tell him these things by working this method into conversation, though he makes it look effortless and never actually says the trope name.
* In Sir Creator/WalterScott's ''The Monastery'', the courtier Sir Piercie Shafton, who speaks in high-flown Euphuist terms, is disguised as a milk-maid; questioned as to who he is, he replies, "I am she, O most bucolical juvenal, under whose charge are placed the milky mothers of the herd." His disguise is unsuccessful.
* In Christie Golden's ''[[Literature/TheShatteringPreludeToCataclysm World of Warcraft: The Shattering]]'', Anduin Wrynn deduces that Jaina Proudmoore has been meeting with Thrall in this manner.
---> '''Anduin''': I don't mind. But then again, I don't have secret meetings with orcs in the middle of nowhere.
---> '''Jaina''': How did--
---> '''Anduin''': Yes! I was right! You were out meeting Thrall!
* In the ''Franchise/DoctorWhoExpandedUniverse'' short story "Walkin' City Blues", the Doctor bursts into the BigBad's office and announces he's seeking justice for Boko Berikuka. When the man launches into a rehearsed spiel about "Boko Berikuka" being a meaningless phrase used by the citizenry, the Doctor points out an innocent man would have called the police, not tried to dodge a question that hadn't actually been asked.
* In Belorussian writer Olga Gromyko's ''Witch'' cycle, the titular witch Volha once uses this trick to find the shapeshifting monster natsyga. It becomes known that the natsyga hides among the castle servants. Volha tells one of the maids: "Why don't you assume your real shape?"
---> '''The maid''': How did you guess?
---> '''Volha''': I didn't. You are the sixth one I told this. Others just thought me crazy.
* In M. K. Wren's ''Phoenix Legacy'' trilogy, Val Severin finds new Phoenix member Alex Ransom looking up some information relating to the fallen Peladeen Republic ... and the fact that the missing and presumed dead heir of the Peladeen Lord had the same name as one of the Phoenix Councilors. Shocked, Val asks how much Alex has been told about "the Peladeen Alternative"; it's top secret. Alex smiles and admits that all he knows is that the Councilor in question is key to the Peladeen Alternative. He never gets around to telling Val that he hadn't even heard that term until she blurted it out.
* In the third book of ''Literature/TheActsOfCaine'', Caine meets a spy for an old friend of his, and instructs the spy to take a message to her. The spy plays dumb for a while, until Caine offers to explain what gave to spy away (so that he can correct the mistake). The spy admits it would be useful to know how Caine was so sure. Caine just says "I wasn't sure."
-->'''Caine:''' Fuckin' amateur.
* In Literature/TheElricSaga, this is how Elric finds out that [[spoiler: his cousin Yyrkoon is trying to obtain the [[SoulCuttingBlade magic Black Swords]], Stormbringer and Mournblade]].
* ''Literature/OneFlewOverTheCuckoosNest'': [=McMurphy=] runs through the hallways of the asylum warning the patients that an orderly is on their way to check on them. Everyone stops what they're doing and pretends to sleep, including Chief Bromden, the narrator. After it turns out to be a false alarm, [=McMurphy=] casually says to Bromden, "Hey Chief, I could've sworn they told me you was deaf!" Bromden had been pretending to be deaf and mute for years before [=McMurphy=] showed up.
* In the novel ''Literature/TheGunsOfNavarone'', the saboteurs, who are posing as Greek fishermen, are confronted by a German caique. When the Germans tell them in English to lower the sails, Captain Mallory is terrified that the captain of their fishing boat and youngest member of the group, Lieutenant Andy Stevens, will fall for it and reply, because the fishermen they are poising at would not know English. Not only does Stevens stare at the German in utter incomprehension, when the man continues to give orders in English, the Lieutenant has the cheek to tell him (in Greek) that he doesnít understand German and asks him to speak in his language.
* This is the reason all of Remo Williams's aliases are Remo 'Something'. While capable of dodging bullets and shattering steel, he often forgets an elaborate alias while on a case.
* In Ben Elton's Dead Famous, Inspector Coleridge manages to get an on-stage confession from Geraldine Hennessy revealing her as the killer in this fashion. After working out how she'd used one of the house tasks to kill Kelly unnoticed- but still without definitive proof- he films a fake evidence tape of the murder using his assistants as actors and airs it at House Arrest's finale show. Geraldine, predictably, takes the bait and and starts raging about how her lackey was supposed to have burned the tapes- whilst he's in the control room, pointing out that he DID burn them and what a complete dupe she's just made of herself.
* In Douglas Hulick's first novel, ''Among Thieves'', the protagonist, Drothe, pretends to be working for one crime lord, but actually owes allegience to that crime lord's nemesis. Midway through the novel, a secondary character figures this out, and asks Drothe how long that's been the case. Drothe asks how she found out: she replies, "you just told me now, you son of a bitch!"
* Literature/HerculePoirot confronts a murderer, in [[spoiler:DeathInTheClouds]].
-->'''Poirot''': You left your fingerprints on the bottle.\\
'''Murderer''': You lie! I wore--\\
'''Poirot''': Ah, you wore gloves?
* Literature/MontagueEgg has reason to suspect that a man in the same room is a wanted fugitive, and so shouts his name, telling him to look out. The man answers...
* In the ''Literature/{{Relativity}}'' story "Tempest," Matthew Bruce (who works for a secret government agency) has recently run into a mysterious man who calls himself Phanthro. Since he doesn't know if Phanthro is another spy or someone unrelated, he outright asks his boss who Phanthro is. His boss responds with a genuinely puzzled "I don't know," meaning that he didn't actually know. If he had known, he still would have answered "I don't know," but it would have sounded practiced and forced.
* In ''Outcast of {{Literature/Redwall}}'', Veil is up to his usual tricks, stealing small objects from Redwallers. When the Abbess claims that a special dye used will turn the thief's paws red, Veil starts scrubbing and scrubbing, seeing his paws turn red before his eyes. Then he overhears a conversation revealing how to remove the dye, and hurries to wash his hands... except, of course, that it actually ''was'' dye this time. Being caught, aha, red-handed causes him to be [[TitleDrop cast out fromthe Abbey.]]

[[folder:Live Action TV]]
* Shows up in ''Series/LawAndOrderSpecialVictimsUnit'':
-->'''Eliot:''' Is this a patient of yours? [''shows picture of suspect'']\\
'''Psychiatrist:''' I am not at liberty to say.\\
'''Eliot:''' You just did. Confidentiality only applies to patients.
** Which is completely ridiculous, because that's the answer any psychiatrist with half a brain would give regardless of whether or not they even recognized the person. They cannot confirm ''or'' deny. A neutral answer is the only thing that a psychiatrist--or any physician--should ever give.
** ''Series/LawAndOrderUK'': The detectives have arrived at a junkyard to look for a murder suspect. The supervisor denies that he's there. Suspecting otherwise, DS Devlin very casually calls out, "Oi, Freddy!" Sure enough, the "Freddy" in question looks up, then further confirms his identity by bolting when he sees the cops.
* The series ''Series/KnightRider'' did this numerous times. On one occasion, a woman impersonated her recently murdered mother to flush out the killer; on another, a blind woman pretended to drive, suggesting to the criminals that she might have witnessed their deeds.
* Michael Westen on ''Series/BurnNotice'' pulls a scheme called a "reverse interrogation," in which he lets the criminal interrogate ''him'', and hopes the bad guy will give away important information in his questions. (He does.) TruthInTelevision, as intelligence agencies often consider the questions their opposite numbers have as being just as informative as actual information: it tells them what the other side does or doesn't know. One of the reasons double agents are rarely just given "shopping lists" for specific pieces of intelligence, instead of vague areas of interest.
* Elaine pulls this trick on George in "The Red Dot" episode of ''Series/{{Seinfeld}}''.
-->'''Elaine:''' Hey, George. Did you buy that sweater, knowing the red dot was on it because you could get it at a discount? Jerry told me that you did.
-->'''George:''' ''(Turning to Jerry)'' You told her?! How could you tell her? What kind of friend are you?
-->'''Jerry:''' I didn't tell her, you stupid idiot! She tricked you!
** She tries it again on Jerry in that same episode, but he sees through it.
--->'''Elaine:''' Did you leave that drink by Dick on purpose, knowing he's an alcoholic?
--->'''Jerry:''' Absolutely not.
--->'''Elaine:''' ''(bluffing)'' Really? Because George said that you did.
--->'''Jerry:''' Nice try.
** A nice subversion in this case, as Jerry is telling the truth.
* ''Series/{{Angel}}'', "Blind Date": Angel throws an object at a woman claiming to be perfectly blind; she catches it out of the air perfectly. Of course, she actually ''is'' completely blind, and he knows it... the point is how the court full of people react to this.
* In an episode of ''Series/TheAgency'', an undercover agent has replaced a person who's known to be allergic to dogs, so he reacts accordingly whenever there's a dog in the room. He's discovered when his suspicious contact places a dog nearby but out of sight and he fails to develop a stuffy nose.
* Happens on an episode of ''Series/JudgeJudy''. Two boys are being accused of stealing a girl's purse and stealing items out of it. The boys deny that they ever touched the purse. Judge Judy, already suspecting the boys of lying, asks the plaintiff to list off the things that were in her purse.
--> '''Plaintiff:''' ...I had gift cards in there, my earpiece, and a calculator.
--> '''Defendant #2:''' There was no earpiece in there, ma'am.
--> '''Judge Judy:''' (Laughing) I love it! I love it. Judgement for the plaintiff.
* ''Series/{{Monk}}'':
** In "[[Recap/MonkS2E7MrMonkAndTheSleepingSuspect Mr. Monk and the Sleeping Suspect]]", the identity of a mail bomber is confirmed when he panics at the sight of someone opening one of his custom-made packages. He shouldn't have known about the bombings because he had been in a coma when they took place. (If you're curious about how he managed to set off the bombings while ''in a coma'', watch the episode in full).
** In another episode, Monk cleared Willie Nelson's name by proving that the other suspect wasn't blind (or at least, not completely blind)--he had a streaker run past her, and she reacted.
** In yet another episode, the murderer had to make sure that his wife's corpse was found without revealing that he had killed her, so he [[spoiler:staged it to look like a psychic had found the body.]] Monk trapped him by [[spoiler:getting the psychic to accuse him of murder, thus forcing him to discredit her--and he helpfully though inadvertently confessed in the process.]]
* From ''Series/{{Dexter}}'':
-->'''[[ScaryBlackMan Doakes]]''': That's all you care about, is your job. Even if it meant doin' Pascal's man to get it back.
-->'''[[PointyHairedBoss LaGuerta]]''': How did you know about Bertrand?
-->'''[[ScaryBlackMan Doakes]]''': I didn't for sure until just now.
* In the ''Series/{{MASH}}'' episode "Out of sight, out of mind," Hawkeye gets temporarily blinded by an exploding camp stove; and goes to sit in a nurses' tent for a while as he's at loose ends. One of them is cautious about undressing with a man in the tent, even thought he can't see her. At the end, after he is cured, he wraps his head back up again and goes back into the same tent, tells them he has had a relapse, and suggests that they would be perfectly safe undressing. One of them promptly tosses a mug at him, which he catches perfectly; and they throw him out of the tent with some alacrity.
** An earlier episode had a rash of thefts occur in the 4077th, with the stolen articles found in Hawkeye's footlocker. To catch the real thief, Hawkeye stages a conversation with Henry to be broadcast over the PA, saying the equipment to get fingerprints off the stolen items is en route. The items are subsequently stolen from Henry's desk. Hawkeye then gathers all the "suspects" (everyone who had something stolen, or simply held a grudge against Hawkeye) to the mess hall, where he says he treated the stolen goods with chemical that would turn the thief's fingernails blue. The culprit turns out to be [[spoiler:Ho-jon, who was going to sell the stolen goods on the black market to get money to smuggle his family out of Korea. He gives himself away by hiding his hands under the table when Hawkeye makes the "reveal".]]
* ''Series/TheMentalist'' - Patrick Jane and the team encounter a hooker who seems to know only Chinese, but when Jane comments on an imaginary hideous thing on her shoulder, she nearly jumps out of her skin. Busted.
** There was also a similar thing when they suspected a [[VictimOfTheWeek dead guy]] was a member of a fancy private club. Jane just waltzes in, calm and confident, then (paraphrased):
-->'''Receptionist:''' Sir? This is a private club, I'm afraid you...
-->'''Jane:''' Oh, that's fine, I'm a member. My name is [[VictimOfTheWeek ]].
-->''A man sitting nearby approaches''
-->'''Man:''' Excuse me? I happen to know Mr. [[VictimOfTheWeek ]], and '''you''' are not him.
-->'''Jane:''' Thank you, for confirming that he was a member.
* ''Series/StargateSG1'': This trope is used and parodied in the episode "1969." The team is stranded in a top-secret Air Force facility in 1969, and [[TimeTravelersAreSpies are suspected of being spies]]. An Air Force interrogator comes in:
--> '''Airman:''' Вы советские шпионы? (Vy sovetskie shpiony?)
--> '''Daniel:''' Нет! (Nyet!)
--> '''O'Neill:''' Daniel?
--> '''Daniel:''' He just asked if we were Soviet spies, I...
--> '''O'Neill:''' ''[glares]''
--> '''Daniel:''' Um.
** In another episode, when preparing to give the Aschen some Stargate codes, Samantha Carter then asks one of the Aschen what a particular word means. The Aschen, not realizing the repercussions of what would happen, simply answered "sterility," in essence admitting that the drug they were giving the Tau'ri would actually give them sterility, making quite clear of the Aschen's ill-intentions towards Earth.
* Used in ''JustGoodFriends'' where Vince has been unfaithful to Penny. Again.
--> '''Penny:''' Why did you take that girl home?
--> '''Vince:''' (sigh) Who told you?
--> '''Penny:''' (sadly) You just did.
* In the ''Series/{{Lost}}'' episode "The Cost of Living," Jack has seen x-rays and believes they are Ben's, so he questions him about symptoms. Ben's reaction gives him away. Later he asks Juliet why she told Jack about his tumor, to which Juliet replies that she didn't; Ben did.
* On ''Series/{{House}}'', Foreman finds out about Thirteen's [[BiTheWay bisexuality]] this way.
** Earlier in the series, House is talking to an 18-year old kid who is taking care of his mother. He later puts an X-ray on the lightboard, and says he can tell the person is about 15. The kid confesses to lying about his age. After a brief conversation, House reveals that it wasn't even the kid's X-ray.
* [[SubvertedTrope Subverted]] in an episode of ''Series/QuantumLeap'' in which Sam leaps into the body of a blind musician, and must pretend to be blind even though he's kept his sight. The mother of the leapee's girlfriend catches him apparently saying something that indicates he can see, and concludes that the leapee must have been a sighted fraud all along. When she tries to out him by flicking a lighter in front of his face, however, he genuinely can't see it because he's just been temporarily blinded by a camera flash.
** A similar, more painful, subversion occurs on an episode of ''Series/ArrestedDevelopment''. Michael tries to prove a blind woman is only faking her condition by [[ThrowTheBookAtThem throwing a book]] at her. Unfortunately, she's been temporarily blinded for real and the book hits her in the face.
* In ''Series/{{Rome}}'', this happens in a manhunt for Cleopatra's son.
-->'''Officer''': [Latin] Right, be off with you. (turns away) [Egyptian] Please bless us with your forgiveness, sacred majesty.
-->'''"Greek slave"''': [Egyptian] Granted, mortal.
-->''(fight scene)''
** In this same series, Atia uses this tactic to expose Octavia's relationship with Agrippa.
* In one episode of the sketch show ''Series/SmackThePony'', two women and one man are being held hostage alone in a room somewhere. One of the women tells the others that her name is some male one. This puzzles the second woman and she keeps asking for explanations for it, but the other just maintains it just is that way. Eventually we see the second woman whispering the other various female names while she sleeps, until she reacts to one and has to admit that was her real name all along; she was just fooling the others as a joke.
* The bad guys tried this quite frequently on ''Series/MissionImpossible'', but one notable case had a gangster see Rollin (playing a deaf waiter) react slightly when a large amount of money was mentioned. In order to test the him, the gangster fires off a revolver next to his ear. Rollin fakes not hearing it, passes the test, and reacts in agony at the pain when he gets out of sight.
** Another episode had the team infiltrating a camp where foreign agents were being trained to pass as Americans. Rollin intentionally blows one such test to prove he's a "genuine" newbie who wouldn't know how Americans would act.
** And in yet another, he catches a glass vase abruptly tossed at him by a foreign spy, who knows the spy Rollin is impersonating is left handed.
* In ''Series/StarTrekDeepSpaceNine'', Dr Bashir is up for a major medical award. He insists that there is no chance of victory for him, and so he does not wish to discuss it.
--> '''Odo:''' In that case, why are you working on your acceptance speech?
--> '''Bashir:''' (Hides pad) How did you know?
--> '''Odo:''' (smugly) Just a guess.
** Another occurrence appears in the episode "The Ascent", in which Odo is delighted to receive orders to arrest Quark and bring him to a Federation court, but isn't told ''why''. He drops several clues to Quark that he ''does'' know, such as "Oh, I think you KNOW why I'm arresting you," trying to invoke this trope. It works, but not in time to prevent the Orion Syndicate from trying to blow up their ship, leaving them stranded on an uninhabitable planet. It turns out Quark wasn't even being charged with a crime, but rather subpoenaed as a reluctant/unwilling witness against the Syndicate, which is why they're after him. Quark and Odo are both incensed at the ''each other'' when they discover the bomb which was planted on the shuttlecraft. Quark is mad at Odo for trying to invoke this trope on him, while Odo defensively lashes out that if Quark had just spilled the beans they'd have had ''a lot'' more security in place for their trip.
* One ''Series/{{Bones}}'' episode ends with her offering everybody in the [[VictimOfTheWeek victim's]] funeral a cup of tea "from his own private stash. The same that was his last drink." [[spoiler:The same one that was poisoned by the victim's mother.]]
* In an early episode of ''Series/{{Merlin|2008}}'', Gaius is certain Merlin is a wizard, but wants to see it for himself. He "accidentally" knocks a pitcher of water off the table, causing Merlin to react by using magic to freeze the pitcher in mid-air. When Merlin realizes what he's done (as he was explicitly warned not to use magic in Camelot, where it is banned), he releases the pitcher, but not before Gaius points out that stunts like that would blow his cover very quickly.
* Used by Elena in ''Series/TheVampireDiaries''. It doesn't seem like a trick, exactly, if you watch it.
--> '''Elena''': I'm asking you.
--> '''John''': That doesn't mean anything to me.
--> '''Elena''': [[spoiler:As my father, it should.]]
--> '''John''': How did you know?
--> '''Elena''': I wasn't sure, until now.
* Ricky does this to Ben in ''Series/TheSecretLifeOfTheAmericanTeenager'' when asking Ben if he had been to see Adrian.
* In an episode of ''Series/{{CSI}}'', a suspect is confronted with a suitcase that resembles one owned by his victim. Thinking it's the same case, he protests that they're not allowed to break into his car, and the investigators thank him for telling them where to look for the real one.
* Used by [[strike: Sheriff]] Deputy Andy the robot in ''Series/{{Eureka}}'' to confirm that Sheriff Carter and the others had, in fact, [[spoiler: traveled through time and changed the timeline.]]
** An earlier episode had Carter stuck in a GroundhogDayLoop. He was able to figure out the scientist responsible for it when the scientist told Carter he'd sign his redaction papers later. Trouble was that Carter hadn't even gotten the redaction list from Thorn yet that loop and was approaching the scientist because he was [=GD's=] "time guy" and just wanted help on cracking the case.
* ''Series/HogansHeroes'': The gang's always careful about their captors setting up a plant in their barracks. In one episode they decide to test a new American "guest." In the middle of the night, they all start making noise and shouting "FIRE!" - Kinch yells at him, in German, "Quick! Out the window!" Newbie heads straight for the window.
* Used once on ''Series/{{NCIS}}'' when they had a suspect who refused to tell them who he was or which country he came from. They had Ziva speak to him in all the different languages she speaks, and when he stared blankly at her the whole time except for a visible reaction when she spoke Russian, they knew that he was from Russia.
* The second season of ''Series/{{Oz}}'' begins in the aftermath of a prison riot, with an investigator trying to find out who shot and wounded [=McManus=], a [[ReasonableAuthorityFigure high-ranking prison administrator]], and how a prisoner named [[{{Slimeball}} Scott Ross]] was shot multiple times and killed by a weapon that was reported missing from the prison's equivalent of a SWAT team, which later reappeared in the prison armory without explanation. Near the end of the episode, the investigator confronts [=McManus=] and explains a crucial fact [=McManus=] had left out before of his prior account, and which can lead to revealing the identity of the person who killed Ross, a person whom [=McManus=] had been trying to cover for. After a long period of silence, [=McManus=] grudgingly asks "Who told you that?" Three guesses what the response is.
* This priceless exchange from ''Series/WillAndGrace'':
-->'''Jack:''' Oh. Oh, I know. I know what this is. Will told me everything. Grace, you really did it this time!
-->'''Grace:''' (to Will) You told him I slept with Rob?!
-->'''Will:''' Uh, no.
-->'''Jack:''' Works every time.
* On an episode of ''Series/ADifferentWorld'', Whitley's new boyfriend Byron has noticed the tension between Dwayne and Whitley and asks him about it. Unfortunately, in doing so, he learns more than ever expected to--Dwayne confirms Byron's suspicions that he and Whitley had previously been involved, but assures him that the relationship is over and that "Last night was a mistake and it meant nothing".
-->'''Byron:''' Last NIGHT?
-->'''Dwayne:''' [[OhCrap You didn't know.]]
-->'''Byron:''' No, I didn't. You just told me.
* Subverted in the "Who are you" episode of ''Series/BuffyTheVampireSlayer''. After Buffy [[GrandTheftMe swaps bodies]] with her EvilCounterpart Faith, Buffy is apprehended by the police and Faith remains alone with Buffy's mother Joyce. The first thing Joyce says is "Faith", and the changeling indeed reacts involuntarily, so it does looks like Joyce deducted her true identity. However, it turns out she didn't and is just willing to ask "Buffy" about Faith.
* ''Series/NCISLosAngeles'': Deeks does this to Kensi by commenting he didn't see a phobia she'd just mentioned on her online dating profile.
--> '''Kensi''': How did you know that I...
--> '''Deeks''': I do now!
* In the pilot of the American version of ''Series/TheKilling'', Detective Linden pulls one of these on Councilman Richmond:
-->'''Linden''': Oh, and councilman, you might want to call off your dog at the school. He won't find anything.
-->'''Richmond''': And how did you know about him?
-->'''Linden''': I was guessing.
-->'''Richmond''': And I just confirmed it.
* ''Series/TheNanny'': Fran does one of these to C.C. in "Where's the Pearls?" when she guesses that she and Maxwell are trying to keep her away from a celebrity. She's right: it's Creator/ElizabethTaylor!
* From ''Series/{{Glee}}'':
-->'''Mr. Schue''': Wait, who gave you these questions to ask me?
-->'''[[TheDitz Brittany]]''': Coach Sylvester says I'm not at liberty to say.
* In ''Series/{{Scrubs}},'' Turk eventually tricks Carla's brother into speaking English in front of her (she thought he only knew Spanish) by saying explicitly sexual things about Carla in front of him.
* ''Series/BoyMeetsWorld'':
** Mr. Feeny uses this technique on at least two occasions. Both cases involved leading a student he suspects of having committed a certain offense into believing that a friend has ratted them out, to elicit as "You told him?" response from the suspect.
* In the ''Series/GreenWing'' episode "Rumours", while trying to persuade Guy Secretan to deny the rumors that they slept together, Caroline Todd tells him that she knows something embarrassing about him. He [[SuspiciouslySpecificDenial hurriedly denies the rumor that Sue White has penetrated him anally]], which Caroline had not in fact heard.
* In the ''Series/CriminalMinds'' episode "Bloodline", Hotch and Prentiss are doing the GoodCopBadCop routine to try and get the name of a person out of the perp. Hotch then reads off a list of their suspects. The perp reacted at one of the names and shouts "I won't tell you!" and Hotch replies "You just did". The OhCrap look is priceless.
* ''Series/That70sShow'' does this in combination with a ContinuityNod from an earlier episode.
--> '''Red''': You lied when you said you weren't taking the car out of town.
--> '''Eric''': Wait, you knew about that?
--> '''Red''': I do now.
* One episode of the Canadian spy series ''Series/{{Adderly}}'' had the secretary, Mona, trying to determine between V. H. Adderly and a lookalike imposter. She asked them about his name: "The V is for Virgil. What is the H for?" When one of them said that the H was for Homer, she knew at once that ''that was the imposter'' -- because the real Adderly knew she did not know his middle name.
* ''Series/BeverlyHills90210''. Steve suspects (correctly) that his new girlfriend is a social climber and a gold-digger. After her less-than-thrilled response to the bracelet that he gives her, he accuses her of already knowing who his mother (a famous former TV star) was long before she approached him:
-->'''Girl:''' "How did you know that?"
-->'''Steve:''' "I didn't. You just told me"
* In the ''Series/TwoAndAHalfMen'' episode 'Aye Aye, Captain Douche', Berta uses this to deduce one of the possible reasons Charlie was sleeping on the couch:
-->'''Berta:''' "Did [Chelsea] find the Polaroids?"
-->'''Charlie:''' "How did you know about the Polaroids?"
-->'''Berta:''' "I didn't. You just told me"
* ''Series/{{Sherlock}}'' Holmes does this on numerous occasions, notably to get Irene Adler to admit that the compromising photos she took are in that room in "[[Recap/SherlockS02E01AScandalInBelgravia A Scandal in Belgravia]]". In another episode, he pretends to be an old friend of a woman's husband and deliberately gets things wrong in order for her to automatically correct him.
* Carson uses this on Mrs Patmore to find out Mrs Hughes might have cancer on ''Series/DowntonAbbey''.
* In one episode of ''Series/{{Flashpoint}}'', the team had caught a member in a gang gunning for another girl. They knew there were at least two others and wanted the captured member to identify their pictures. The gang member had no intention of helping them but when her eyes lingered a little longer on one of her friends, Parker picked up the picture and she immediately blurted out "But I didn't say anything!"
** In the series finale, the team believed the bomber placed ten bombs, based on the list of complaints they've been receiving. After five bombs were defused/detonated, Jules talked with the bomber and asked him "Where are the other five bombs?", to which he was surprised that they knew there were five left, confirming their theory.
* From an episode of ''Series/{{Suits}}'':
-->Harvey: Did you go see Joy, after I told you not to?
-->Mike: How did you know?
--> Harvey: I didn't. Until now.
* Frequently done by Cal Lightman in ''Series/LieToMe'' to get the criminal-of-the-week to reveal him/herself. One case involved a woman in the US Army claiming to have been repeatedly raped by her commanding officer. While Cal quickly figures out that she's lying, she actually did that for her friend whom that same officer was raping. He would threaten to put her in the front vehicle of a convoy, which is often the first to be hit in an ambush or by a mine. When questioning him in front of the base commander, Cal pushes the point until the officer unintentionally yells out that he never puts her in the first vehicle. The base commander realizes the implications of this: he doesn't put her in the first vehicle, even though he's supposed to as part of the normal rotation, because she's sleeping with him. The base commander calls the [=MPs=] to take the officer away.
* A non-undercover example in the "[[Recap/DoctorWhoS34E3RobotOfSherwood Robot of Sherwood]]" episode of ''Series/DoctorWho''. Clara uses a similar method to get information out of the Sheriff Of Nottingham. She even explains that this is one of the Doctor's tricks: the easiest way to get information out of someone is to convince him that you already have it.
* In one episode of ''Franchise/{{Dragnet}}'', Friday and Smith are questioning a man suspected of beating a father and daughter, the father fatally.
-->'''Smith''': His daughter saw you.\\
'''Suspect''': She can't have. [[TooDumbToLive The lights were out]].
* An episode of ''Series/{{Poirot}}'' features this exchange:
-->'''Poirot:''' Tell me, you have lived in New Zealand?\\
'''Suspect:''' ''[Astonished]'' However did you discover that? Mind you, it is known.\\
'''Poirot:''' Is it? I have tried numerous ways to discover it without success.\\
''[The suspect looks [[DeathGlare pissed off]] and [[OhCrap cornered]].]''
* In ''Series/TheKicks'', Emma tricks Mirabelle into revealing [[spoiler: Devin's injured ankle]] this way. Mirabelle notes that she walked right into it.
* In an episode of ''Series/{{Lou Grant}}'', newspaper reporter Billie Newman attempts to break the ice with a street youth she is trying to befriend by using this ploy, stating something she suspects about him as if it were fact, and when he asks her in astonishment how she knew that, she replies with the trope namer, "You just told me...it's an old reporter's trick." These words come back to haunt her however, when they are smugly quoted by the same teenager after he tricks her into giving away some vital information using her own ploy.
* In ''LiveAction/MakoMermaidsAnH2OAdventure'', Evie attempts to bluff Cam into telling her Zac's secret by announcing that he finally told her, and that she completely understands. It sorta works, with Cam showing relief and even outright telling her that Zac should have told her in the first place, which at least confirms that Zac has a secret to hide. However, Evie legitimately has ''no idea whatsoever'' what Zac's secret is, and accidentally gives the bluff away by saying it's something everyone has to go through. Since Cam knows full well that the secret in question is ''suddenly gaining merman powers'', he doesn't buy it past that.
* ''Series/DearWhitePeople'': How Coco learned about [[spoiler:Troy's affair with Neika]].

* Used in [[Film/NintendoPowerPromoVideos a promo video]] given out by ''Magazine/NintendoPower'' promoting ''VideoGame/StarFox64''; the two bad guys, apparently representing rival companies Sega and Sony, kidnap a tester (Peter) and lab guy (Bob) to find out the game's secrets.
-->'''Bob:''' Peter, you didn't mention the ''Rumble Pack'', did you?!
-->'''Peter:''' ''(FacePalm)''
-->'''Sony Guy:''' No... 'Bob'...you just did.
-->'''Bob:''' I did?
-->'''Peter:''' You did.

[[folder:Video Games]]
* In ''VideoGame/Uncharted3DrakesDeception'', [[BigBad Marlowe]] tells Nate Drake that she knows where Ubar is because 'you told us, Nathan.' while he was under the influence of a TruthSerum.
* In ''VideoGame/SonicAdventure2'', Dr. Eggman uses this ploy to confirm that he correctly guessed that one of the two identical-looking Chaos Emeralds was a fake, due to having looked at readings from the 2 separate Emeralds at his pyramid base earlier. (Not that it's very likely Tails would knowingly give Eggman the real one if he had a fake one as well.)
-->'''Eggman:''' You thought you [[BluffTheImposter could trick me with that fake Emerald]], didn't you?
-->'''Tails:''' So... how did you know it wasn't the real one?
-->'''Sonic:''' ''(cutting him off)'' ''TAILS!''
-->'''Eggman:''' Heh. Because you just TOLD me, fox-boy.
** Tails' facial expression after it seals the deal; it's a mixture of OhCrap and NotBad.
* In the third case of ''VisualNovel/PhoenixWrightAceAttorney – Trials and Tribulations'', [[spoiler:Phoenix gets the real killer to incriminate himself by presenting a bottle of the victim's ear medicine, and claiming that it contained the poison used to kill the victim. This is a {{Blatant Lie|s}} to anyone who had been watching the trial, as the real poison bottle had already been presented. The killer had ''not'' been watching the trial, nevertheless he proceeds to call Phoenix an idiot and gives an accurate description of the real poison bottle, proving that he is the killer]].
* Used in ''[[VideoGame/FireEmblemTellius Fire Emblem: Radiant Dawn]]''. Heather, a small time thief, confronts Yeardley, a general working on Duke Ludveck's orders, about his attempts to get the townspeople of Crimea to revolt against Elincia.
-->'''Heather:''' So! You're the ones sent by Ludveck of Felirae?! You've been stirring up these little revolts all over the place!
-->'''Yeardley:''' What?! How did you know?!
-->'''Heather:''' I see things here and there. But half of it was just a guess! ...Judging by your reaction, though, it seems I was right.
** Later on, when Marcia confronts her useless brother Malakov as he tries to avoid fighting Imperial Army troops:
-->'''Marcia:''' ...I think I see. You owe them money, don't you? Isn't that the real reason why you don't want to see them, cheese breath?
-->'''Makalov:''' W-when did you learn to read minds like the herons!?
-->'''Marcia:''' I can't, you spineless sea cucumber! It's just so typical of you that I guessed!
* A variant where "Stan" doesn't let "Ben" know when he figures it out. In ''VideoGame/KingdomHeartsChainOfMemories'', Axel is sent to Castle Oblivion because Marluxia and Larxene are suspected of plotting against the Organization. About halfway through the game, Axel chats with Larxene about the plan they have for [[TheHero Sora]] as Larxene heads down to meet Sora.
-->'''Axel:''' Don't forget. Sora is the key. We need him if we're going to take over the Organization.
-->'''Larxene:''' I know that you're in on it too, but keep it under your hood. At least until the time is right.
-->'''Axel:''' ''*after Larxene leaves the room*'' You would have been wise to do the same, Larxene.
* In ''VideoGame/{{Suikoden}}'' Viktor uses this on Tesla in order to recruit him since Tesla just wants to live a quite and simple life and pretends to be Albert Onyx. The party already learned that he will pretend to be Albert from Kimberly before visiting him.
-->'''Viktor:''' You're Tesla, the Scrivener, right?
-->'''Albert:''' Goodness, no. My name is Albert Onyx. My people have lived here for generations.
-->'''Viktor:''' Really? Then what is your mother's name?
-->'''Albert:''' Ummm, her name is Marianne Onyx.
-->'''Viktor:''' And your father?
-->'''Albert:''' I believe it was... Ah... Allen Onyx.
-->'''Viktor:''' Grandmother!
-->'''Albert:''' Uhh... let's see... Leah Onyx.
-->'''Viktor:''' Hey Tesla.
-->'''Albert:''' Yes?
-->'''Albert:''' .............!
-->'''Albert:''' I mean... that's not my name, Tesla.
-->'''Viktor:''' Do you give up?
-->'''Tesla:''' All right. Mathiu wants me, right? I prefer to lead a quiet life.
-->'''Viktor:''' Stop yapping and get ready to leave
-->'''Tesla:''' O-OK. My god, how unlucky I am.
-->'''Tesla:''' Led back into a life of crime. *Tesla joins*
* On the final day of Golden Playhouse mode in ''VideoGame/{{Catherine}}'', [[spoiler: Vincent confronts Boss, the barkeep at the Stray Sheep, about the fact that he was the only other person able to see Catherine, and accidentally gets Boss to blab about his involvement in the reoccurring nightmares Vincent and the other patrons have been having.]]
* Piros the 3rd of VideoGame/DotHackGU claims that Haseo doesn't deserve to know his name... then introduces himself in an over-the-top manner. This trope's name is Haseo's exact response to this.
* In VideoGame/StarOceanTillTheEndOfTime, Fayt tricks Cliff into revealing that he has been in contact with Mirage and even gets Cliff to tell him what their conversation was about by simply asking "So what did Mirage say?" Cliff is pretty impressed by his craftiness.
* ''VideoGame/XenobladeChronicles2'': After being captured, Nia is so sure they're after the names of the crew she was with previously that she's a little poleaxed when the Inquisitor question her reveals she's more interested in Nia's more recent traveling companions.
-->'''Nia:''' Rex and Pyra?
-->'''Morag:''' Well, that was easy.
-->'''Nia:''' [[OhCrap (Dammit!)]]

[[folder:Web Comics]]
* A creative application of the trope occurred in ''Webcomic/RipAndTeri''. Agent XI knows Rip has infiltrated a TV studio in disguise. A few days earlier, Rip had encountered XI in a janitor uniform, so XI stations himself inside the studio in the same uniform. Rip's startled reaction to seeing the same "janitor" he fought earlier gives him away.
* From ''Webcomic/{{Narbonic}}'', [[http://narbonic.com/comic/april-1-6-2002/ during the D-Con]] StoryArc:
--> '''Helen''': You know I'm not "Dave Pretorius." There's no such man. You know I'm really your own daughter in disguise. You know I infiltrated D-Con to crack the Dave Conspiracy, having no idea you'd already done it! ...And you didn't actually know any of this until I voluntarily told you, did you?
--> '''Dr. Narbon''': I'm '''such''' a great mother.
* Cleverly done in Webcomic/DanAndMabsFurryAdventures:
-->'''Bigs:''' (thinks) If you are trying to read my mind I swear I will deck you.
-->'''Dan:''' Huh? How would you know that I--
* Used in ''WebComic/EightBitTheater'' [[http://www.nuklearpower.com/2009/01/06/episode-1079-verbal-flanking/ by Thief]] figuring out he doesn't owe his life to anyone after all.
-->'''Crow:''' How did you find out?
-->'''Thief:''' I only suspected it until you confirmed it for me just now.
** And [[http://www.nuklearpower.com/2004/02/26/episode-389-of-course-they-knew-that/ in an earlier strip]]:
--> '''Red Mage:''' Wait, we figured that out?
--> '''Thief:''' No one can say we don't know it '''now'''. That's close enough, really.
* In [[http://www.krakowstudios.com/krakow/archive.php?date=20021227 this]] ''WebComic/{{Krakow}}'' comic, Canadian rap sensation Snow tricks one of the characters into admitting that he altered the lyrics while singing one of Snow's songs.
-->Case: But...but...How did you know that?
-->Snow: I only had suspicions, but you just confirmed them!
* In ''Webcomic/TwoEvilScientists'', Eggman Nega invokes it [[http://twoevilscientists.smackjeeves.com/comics/564463/fox-hunt-pt-14/ here]] when he's confronting his ancestor
* In [[http://eheroes.smackjeeves.com/comics/2122072/nighthawks/ this]] ''Webcomic/EverydayHeroes'' episode, Mr. Mighty finds out about a planned crime. It works so well, he tries it again on the [[http://eheroes.smackjeeves.com/comics/2122073/oops-i-did-it-again/ next page.]]
* A priest in ''Webcomic/{{Nukees}}'' confirms Gav is a lapsed Catholic by saying "peace be with you" as he leaves, getting an automatic "and also with you."
* In ''Webcomic/ExterminatusNow'' Steve effortlessly got Virus to confirm that the group visiting Cesspool is from [[http://exterminatusnow.co.uk/2011-07-04/comic/the-cesspool/enquiring-minds-want-the-gossip/ Inquisition]].
* Jake, the usual dumb friend, from ''Webcomic/SlightlyDamned'', pulls this one on [[DeadpanSnarker Rhea]] [[AwesomeMcCoolName Snaketail]] to get her to admit to having been [[DeathIsCheap previously]] [[http://www.sdamned.com/2012/09/09152012/ murdered.]]
* ''Webcomic/ServantsOfTheImperium'': Used by Aki in [[http://www.servantsoftheimperium.com/comic.php?comicid=186 strip #181: "Intelligence"]].
* ''Webcomic/DumbingOfAge'' has Mike [[http://www.dumbingofage.com/2014/comic/book-4/02-i-was-a-teenage-churchmouse/lures/ use it succesfully]] on Sal:
-->'''Sal:''' ''(After Mike suggests she seduced a teacher)'' Mike, you been Tailin' me? What do you know?
-->'''Mike:''' Nothing. But cast enough lures, you eventually land a fish.
* How Cohen in ''Webcomic/ButImACatPerson'' confirms the identity of Cybele's Master.
* How Cake Girl in ''Webcomic.{{Gloomverse}}'' [[http://gloomverse.smackjeeves.com/comics/1804848/the-magic-show-part-2-page-5/ figures out the origin of Harold's partial-invisibility]].
* In the "Cliffhangers" theme of ''Webcomic/IrregularWebcomic'', Colonel Haken uses the "Once again, Dr Jones, we see there is nothing you possess which I cannot take away" line. Despite the attempts of his father and grandfather to shush him, Montana Jones replies "But ... what do the Nazis want with the Palladium of Troy? And how did you even know what we were after?!" and Haken smugly concludes "And again, we see there is nothing you can try to find which I cannot find out you are trying to find."

[[folder:Web Original]]
* In ''[[Literature/ShadowOfTheTemplar High Fidelity]]'', after Simon tells Sandra that [[spoiler:he's going to Europe to find [[DatingCatwoman Jeremy]]]]:
-->'''Sandra:''' I could believe this stupid shit from Mike, but I never thought I'd catch you [[spoiler:thinking with your dick!]]
-->'''Simon:''' ...What?
-->'''Sandra:''' You heard me!
-->'''Simon:''' Christ, does ''everyone'' know about it by now? How long have you known?
-->'''Sandra:''' Known for sure? For about-- ''(checks watch)'' --ten seconds.
-->'''Simon:''' Oh Jesus, I walked right into that, didn't I?
* In the new season of ''WebVideo/TheGuild'', this is how Codex admits to [[spoiler: sleeping with Fawkes]].
* From the first ''[[WebAnimation/AwesomeSeries Metal Gear Awesome]]'':
-->'''Psycho Mantis:''' You like men!
-->'''Snake:''' ''You can see into my mind?''
-->'''Psycho Mantis:''' No.
-->'''Snake:''' Fuck.
* From ''Website/NotAlwaysRight'', [[http://notalwaysright.com/should-just-slink-on-out-of-there/43871 "Should Just Slink on Out of There"]]: Customers try to exchange a completely mangled Slinky, with an obviously bogus story that it was broken in its original package. There's an escalator just outside the store, so the attendant makes an educated guess:
-->'''Me:''' So guys. Youíre telling me that you DIDNíT try to push this slinky down the step escalators?\\
'''Customer:''' UhÖ UhÖ So you saw that, huh?\\
'''Me:''' No, but now youíve admitted it, we canít provide you with a new one for something thatís not our fault. Have a nice day!

[[folder:Western Animation]]
* In ''TransformersPrime'', when Arcee has Starscream in her custody, she mentions how Airachnid offlined her partner. Starscream loudly complains about Airachnid "taking credit for that, too". When Arcee mentions she's talking about Tailgate, Starscream asks "who's Tailgate", tipping her off that it was he who terminated [[spoiler:Cliffjumper]]. Unusual for this trope, Arcee didn't have any suspicions toward Starscream until he said he didn't know who Tailgate was: she'd thought that [[spoiler: Cliffjumper]] was killed by some random Vehicons.
* In Disney's ''Disney/{{Aladdin}}'', Jasmine, suspecting "Prince Ali" to be Aladdin, idly mentions Aladdin's friend/pet Abu (whom "Ali" would not know about); Aladdin responds without thinking.
* ''WesternAnimation/TheIronGiant'': Annie Hughes is talking to junkyard owner Dean [=McCoppin=]. She mentions Hogarth (her son) sneaking out to the junkyard, and he asks if she knew about it, and she says "I do now."
* In ''WesternAnimation/IronManArmoredAdventures'', Pepper has a hunch that Tony Stark is Iron Man, so she confronts him about it and he casually asks how she figured it out. You just told me. Though in his defense she did give him some good reasons that he believed she already knew, she was practically just confirming it by this point.
* Azula in ''WesternAnimation/AvatarTheLastAirbender'' uses this to trick Zuko out, not about his identity, but about visiting his Uncle Iroh.
-->'''Azula:''' So, I hear you've been to visit your Uncle Fatso in the prison tower.\\
'''Zuko:''' That guard told you!\\
'''[[MagnificentBastard Azula]]:''' No. You did. Just now.
* In ''WesternAnimation/{{Daria}}'', a DreamSequence that parodies ''Series/MurderSheWrote'' has Daria investigating the murder of Kevin, that she's been framed for. She says that she coated her locker (where the murder weapon was planted) with a clear paint that changes color over time, and the hands of whoever was in her locker would be turning pink any minute. Three suspects check their hands, then she says she made the whole thing up since only the guilty party would look.
* Parodied in ''WesternAnimation/InvaderZim'' episode "Mortos der Soulstealer"
-->'''Dib:''' Zim! I don't know what your plan is, but I'm gonna stop it!
-->'''Zim:''' I am infecting this city with genetically enhanced vermin, but ''you'll'' never know!
-->'''Dib:''' You just told me.
-->'''Zim:''' (after a brief pause) You're LYING!
* ''WesternAnimation/{{Doug}}'': A [[JerkAss douchebag]] student named Willy claims his teacher is incompetent and tries to get her fired. In front of an assembly, Doug asks Willy questions about classic novels, [[ObfuscatingStupidity mangling the details along the way]]. Willy smugly corrects Doug at every turn...but Doug points out that he and Willy learned all of that stuff in the teacher's class, so she has to be decent at her job. Willy has no choice but to drop his suit.
* ''WesternAnimation/TotalDramaRevengeOfTheIsland'': Scott uses this to trick Cameron into revealing Mike's [[SplitPersonality multiple personalities]].
-->'''Scott''': Mike wanted me to let you know that he's thankful you're helping him out with his "problem".\\
'''Cameron''': He told you about his Multiple Personality Disorder?\\
'''Scott''': No. But you just did.

[[folder:Real Life]]
* A shibboleth is a word, sound, or custom that a person unfamiliar with its significance may not pronounce or perform correctly relative to those who are familiar with it. It is used to identify foreigners or those who do not belong to a particular class or group of people. It also refers to features of language, and particularly to a word or phrase whose pronunciation identifies a speaker as belonging to a particular group.
** Wiki/TheOtherWiki gives us [[http://en.wikipedia.org/wiki/List_of_shibboleths a list]].
** The word's origins are in ''Literature/TheBible'' ([[http://www.biblegateway.com/passage/?search=judges%2012:5-6&version=NIV Judges 12:5-6]]), where the word was used as a test to reveal whether someone had a regional accent. The Ephriamites would pronounce it as "sibboleth," thus giving away the fact that they were enemy agents. That makes this one OlderThanFeudalism.
** Dominican dictator Rafael Trujillo conducted a brutal massacre of undocumented Haitian settlers along the Dominican-Haitian border. The action is known as the Parsley Massacre. Suspects not fluent in Spanish either did not know or could not properly pronounce the Spanish word 'perejil' (parsley). The pronunciation of the word by Haitian citizens tended to be with a non-rotative r and an omission of the 'l' at the end of the word.
* Shouting "Attention!" is one method of revealing if someone has military training (an FBI agent did this while interrogating a suspect in the 1998 Nairobi bombing). Shouting "Achtung!" unexpectedly was used among Allied prisoners of war to uncover German infiltrators.
* To tell if someone speaks a language or not, police often ask them to say what color different words are (like the word "[[color:green:red]]" written in green ink). People who speak the language will [[http://en.wikipedia.org/wiki/Stroop_effect take far longer]]. This is because this is the Stroop Test, a psychology tool in which taking longer is ''normal'', under normal conditions.
* A Russian proverbial story tells about a guy who spots a pickpocket in the market. Nobody else sees it, though, so the quick-witted fellow points in the thief's general direction and shouts: "That ''thief's'' hat is on fire!" [[SugarWiki/FunnyMoments The crook instinctively grabs his headgear...]]
* Very similarly, in a Serbian folk tale, St. Sava (the man that established the Serbian Orthodox Church) was asked to use his wisdom to find a thief in a crowd. He replied with "Oh, that's easy. It's the guy with the bee on his hat!" pointing out into the crowd's general direction. Of course, the guy waves his hand to chase off the (nonexistent) bee, and gets caught.
* Pickpockets use this to find people wallets.
** A lateral thinking puzzle asks how police putting up signs warning about pickpockets actually helps the thieves. The solution is that pickpockets hang around the signs. When people see the notices, they automatically check their valuables to make sure they haven't been stolen, showing the thieves exactly where they keep them.
** One TV show about scams showed that thieves sometimes take advantage of this and put up the signs themselves!
** An old trick among pickpockets working in groups is to have one person turn to a friend and (loudly) proclaim "Somebody stole my wallet!" The marks nearby instantly will pat their own wallets, broadcasting the location of their valuables.
** Even more subtly. Most people will subconsciously check their wallet if bumped into in a crowded place. Pickpockets use this to learn which pocket their mark keeps it in before making their move.
* Undercover police officers usually use their own first name to avoid this.
* To avoid this, while agents were in training they would be woken up by instructors in the middle of the night and asked things like "what is your mother's maiden name". The other point was so they would know their cover story so well it may as well have been their own life.
* A member of Allied intelligence in UsefulNotes/WorldWarTwo thought agents were captured and impersonated, so at the end of one of the messages he sent H.H. (for Heil Hitler). The message he got back from the 'agents' also ended in H.H.
* A preteen/teenager joke in Brazil is saying "The hands of whoever just farted are yellow". Whoever looks...
** A similar joke in the United States is to say "Did you know frequent masturbation gives you hairy knuckles?" and then mock whoever takes a moment to check.
* This is why government authorities who are supposed to keep a secret are supposed to use the stock line "I can neither confirm nor deny that" when asked any question vaguely related to secret matters, even if it's not a secret they know or is completely off base. It stops the pattern of "no", "I can't answer that", and "I don't even know what you're talking about" from revealing information.
* Commonly used by parents to trick young children into outing themselves on lies. One variant has the parent use "magic powder", or some facsimile thereof, to supposedly make a child's ears turn colours whenever they lie. Not difficult to spot fibs when the child in question starts conspicuously covering their ears.
** There's an old story with a non-verbal variation. A hotel's guest had valuables stolen by another guest at the hotel. They call in a wise man who hands out sticks, each of the same length, to the guests. He says that they're magic, and the stick given to the thief will grow a certain amount in the night. The guests handed their sticks to the man the next morning, and the thief was the one with the ''shortest'' stick, as he had trimmed it to disguise its growth.
** A story told about the mathematician John Napier says that he believed one of his servants was stealing from him, so he declared that they all had to enter a dark room and touch his rooster (not a euphemism) who would crow if it felt the touch of a dishonest man. Since people were rather fuzzy on the difference between scientist and sorcerer at the time, and it was widely rumoured the rooster was his familiar, this sounded plausible. Afterwards, he explained that the rooster was covered in coal dust, and the thief was the man with clean hands.
** Yet another variant involves a wise man setting up a box, backing a donkey against a hole cut in it, and telling the suspects to enter the box and pull on the donkey's tail. The donkey would only bray for the thief. Of course, the "tail" the people were pulling in the box wasn't actually the donkey's tail, but it was coated in oil, so the thief could be caught dirty-handed (or clean-handed, as the case may be).