History Main / TrustPassword

16th Mar '17 3:42:31 PM AthenaBlue
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* On ''Series/ThirtyRock'', Nathan Lane shows up claiming to be Jack's brother, and Liz is suspicious because Jack has never mentioned a brother and this man pronounces their last name "Dona-hee" as opposed to "Dona-gee." Then he comments that she would be prettier if she didn't scowl, and she knows he's related to [[VitriolicBestBuds Jack]].
* In the first-season finale of ''Series/AgentsOfSHIELD'', Skye convinces Mike she has his son by having Ace repeat what they said to each other in the pilot.



* In one episode of ''{{Series/Bones}}'', a boy is kidnapped. Booth asks the dad what password he can use so the boy will trust him during the rescue. (It turns out to be "Paladin" -- ''i.e.'' "defender of the faith", which as his boss notes is an oddly appropriate one for a Catholic FBI agent.)
* In an episode of ''Series/BuckRogersInTheTwentyFifthCentury'', Buck hijacks a Draconian fighter and must prove to another pilot that he's from Earth. The pilot is someone Buck had previously been stranded in the desert with and had shared stories of the past. In this case, Buck proved who he was by giving a description of OJ Simpson. Since Buck had left Earth in 1987, he had no idea that OJ may or may not have turned out to be a double murderer and since the show was filmed prior to this, neither did the writers.
* ''Series/BuffyTheVampireSlayer'' was never known to use this trope straight, which makes sense, as it was written by Creator/JossWhedon (who also gave us [[Film/XMen1 Wolverine's "You're a dick" line]]):
** Giles tries to prove his identity:
-->'''Giles:''' Cordelia, it's me! It's me!\\
'''Cordelia:''' How do we know it's really you and not zombie Giles?\\
'''Giles:''' Cordelia, do stop being tiresome.\\
'''Cordelia:''' It's him.
** Xander does the [[{{ComicStrip/Peanuts}} Snoopy Dance]] to prove he's Xander for Willow.
** Xander tells a story about one of his early birthdays to prove his identity. He wanted a fire truck but didn't get one, which made him sad, but then the neighbor's house caught fire for real, and he got to see real fire trucks. He adds that he always thought Willow might have set the fire ("if you did you can tell me"). The problem with this is ''(a)'' he's trying to prove he's not his EvilTwin, who would know this anyway, and ''(b)'' Willow wasn't aware that there ''was'' a twin and thus had no reason to doubt he was Xander.
* ''Series/{{Charmed}}'':
** In "That 70's Episode", Prue and Piper convince their past selves to trust them by opening a trick drawer in a cabinet.
** Piper attempts it in another episode, telling their mother they can be trusted because they know she's pregnant with Phoebe. It backfires because not only does she not know, she believes she's infertile.



** In the two-parter "Human Nature"/"The Family of Blood", Martha Jones, a medical student from the future disguised as a maid, uses her knowledge of anatomy to prove that she's more than she seems.
** In the Series Four episode "Forest of the Dead," Professor Song [[spoiler: whispers the Doctor's name into his ear]] to prove that she knows him in the future.



** In [[Recap/DoctorWhoS29E8HumanNature "Human Nature"]]/[[Recap/DoctorWhoS29E9TheFamilyOfBlood "The Family of Blood"]], Martha Jones, a medical student from the future disguised as a maid, uses her knowledge of anatomy to prove that she's more than she seems.
** In [[Recap/DoctorWhoS30E9ForestOfTheDead "Forest of the Dead"]], Professor River Song [[spoiler: whispers the Doctor's name into his ear]] to prove that she knows him in the future.



** From the series six premiere, when Amy needs to get the Doctor to trust her, she tells him a detail only they would know: the Doctor's WackyCravings from their first meeting:

to:

** From the series six premiere, [[Recap/DoctorWhoS32E1TheImpossibleAstronaut "The Impossible Astronaut"]]: when Amy needs to get the Doctor to trust her, she tells him a detail only they would know: the Doctor's WackyCravings from their first meeting:



* An unintentional variation occurs in ''Series/{{Farscape}}''. John is having a normal conversation with Aeryn until he mentions [[spoiler:her baby]] and she doesn't know what he's talking about. This gives away that she is a [[spoiler:bioloid duplicate and the real Aeryn has been kidnapped]].
* In ''Series/JessicaJones2015'', Trish and Jessica decide they need some sort of signal to indicate Jess is not under Kilgrave's mind control. Since Kilgrave would make Jessica pretend like everything's normal, they decide to use a phrase that Jessica [[SomethingTheyWouldNeverSay would never say:]] [[spoiler:"I love you."]]
-->'''Trish:''' You say it, you're still you.
* In one episode of ''Series/LoisAndClark'', a time-traveller is able to enlist Clark's aid by whispering to him, "I know you're Superman, and I need your help."



** In season 4 episode "The Constant," 2004-Daniel tells Desmond to tell 1996-Daniel that [[spoiler:he knows about Eloise, and give him some important numbers for an experiment. This proves to Daniel that Desmond is traveling in time and has spoken to a future version of Daniel]].

to:

** In season 4 episode "The Constant," Constant", 2004-Daniel tells Desmond to tell 1996-Daniel that [[spoiler:he knows about Eloise, and give him some important numbers for an experiment. This proves to Daniel that Desmond is traveling in time and has spoken to a future version of Daniel]].



* In the series 2 premiere of ''{{Series/Misfits}}'', the gang have to deal with a shapeshifter. In order to make sure it's really them, they greet each other with "Monkeyslut!" As befits their general methods, this is horribly ineffective. When one of them does encounter the shifter, he just says it with prompting, and fails to notice the shifter's look of confusion.
* ''Series/QuantumLeap'': Sam has leaped into an illiterate murderer on the run who is holding a woman and her daughter hostage. He decides to drop the {{masquerade}}, telling her he's a doctor from the future in a TimeTravel experiment. She doesn't believe him. Then he notices her medical textbook, and she reveals that she's in medical school. So he has her quiz him on medical stuff to prove that he's telling the truth. At first she still doesn't believe him, saying that he looked at the book already, so could have memorized the information. Sam quickly fires back: "When was the last time you met an illiterate speed-reader?"
* In an episode of ''Series/SaluteYourShorts'', Camp Anawana is playing a very intense game of CaptureTheFlag with a rival camp. Pinsky ends up going to Donkeylips for help. Donkeylips and Z.Z. aren't sure if he's real or an impostor, so Donkeylips decides to ask him something that he told him earlier in the episode.
-->'''Donkeylips:''' What are the four S's of warfare?\\
'''Pinsky:''' Strength, strategy, and surprise.\\
'''Z.Z.:''' It's Pinsky!\\
'''Donkeylips:''' Shhhh!\\
'''Pinsky:''' That's the fourth S.
* TimeTravel was the whole point of ''Series/SevenDays'', and the team set up a code phrase for the protagonist to use so that they'd always know when he had shown up from the future, and they weren't dealing with a hoax. The password used is Frank contacting Backstep and identifying himself as "Conundrum". Interestingly, it was never used this way after the first episode, once the team knows full well who he is -- it's just a signal for them to put him through to the right people.
* In ''Series/SleepyHollow'', Ichabod and Abbie use a fist-bump to identify each other in Purgatory, as Abbie had recently taught it to Ichabod. Also while in Purgatory, Abbie correctly identifies a Crane imposter since the fake didn't pronounce her title using Crane's insistent British pronunciation: "Lef-tenant".
* ''{{Series/Smallville}}''
** In "Transference", Clark Kent and Lionel Luthor [[FreakyFridayFlip swap bodies]]. In Lionel's body, Clark convinces Ma Kent it's really him by telling the story of how he discovered SuperSpeed at age 6.
** Subverted in "Apocalypse": Clark tries to prove he's a friend to Chloe by revealing some of their past experiences, but since he's in an AlternateUniverse where they have never met, it fails.



* TimeTravel was the whole point of ''Series/SevenDays'', and the team set up a code phrase for the protagonist to use so that they'd always know when he had shown up from the future, and they weren't dealing with a hoax. The password used is Frank contacting Backstep and identifying himself as "Conundrum". Interestingly, it was never used this way after the first episode, once the team knows full well who he is -- it's just a signal for them to put him through to the right people.
* In one episode of ''Series/LoisAndClark'', a time-traveller is able to enlist Clark's aid by whispering to him, "I know you're Superman, and I need your help."
* ''Series/{{Charmed}}'':
** In "That 70's Episode", Prue and Piper convince their past selves to trust them by opening a trick drawer in a cabinet.
** Piper attempts it in another episode, telling their mother they can be trusted because they know she's pregnant with Phoebe. It backfires because not only does she not know, she believes she's infertile.



* In an episode of ''Series/BuckRogersInTheTwentyFifthCentury'', Buck hijacks a Draconian fighter and must prove to another pilot that he's from Earth. The pilot is someone Buck had previously been stranded in the desert with and had shared stories of the past. In this case, Buck proved who he was by giving a description of OJ Simpson. Since Buck had left Earth in 1987, he had no idea that OJ may or may not have turned out to be a double murderer and since the show was filmed prior to this, neither did the writers.
* ''Series/BuffyTheVampireSlayer'' was never known to use this trope straight, which makes sense, as it was written by Creator/JossWhedon (who also gave us [[Film/XMen1 Wolverine's "You're a dick" line]]):
** Giles tries to prove his identity:
-->'''Giles:''' Cordelia, it's me! It's me!\\
'''Cordelia:''' How do we know it's really you and not zombie Giles?\\
'''Giles:''' Cordelia, do stop being tiresome.\\
'''Cordelia:''' It's him.
** Xander does the [[{{ComicStrip/Peanuts}} Snoopy Dance]] to prove he's Xander for Willow.
** Xander tells a story about one of his early birthdays to prove his identity. He wanted a fire truck but didn't get one, which made him sad, but then the neighbor's house caught fire for real, and he got to see real fire trucks. He adds that he always thought Willow might have set the fire ("if you did you can tell me"). The problem with this is ''(a)'' he's trying to prove he's not his EvilTwin, who would know this anyway, and ''(b)'' Willow wasn't aware that there ''was'' a twin and thus had no reason to doubt he was Xander.
* In one episode of ''{{Series/Bones}}'', a boy is kidnapped. Booth asks the dad what password he can use so the boy will trust him during the rescue. (It turns out to be "Paladin" -- ''i.e.'' "defender of the faith", which as his boss notes is an oddly appropriate one for a Catholic FBI agent.)



* In the series 2 premiere of ''{{Series/Misfits}}'', the gang have to deal with a shapeshifter. In order to make sure it's really them, they greet each other with "Monkeyslut!" As befits their general methods, this is horribly ineffective. When one of them does encounter the shifter, he just says it with prompting, and fails to notice the shifter's look of confusion.
* An unintentional variation occurs in ''Series/{{Farscape}}''. John is having a normal conversation with Aeryn until he mentions [[spoiler:her baby]] and she doesn't know what he's talking about. This gives away that she is a [[spoiler:bioloid duplicate and the real Aeryn has been kidnapped]].
* ''{{Series/Smallville}}''
** In "Transference", Clark Kent and Lionel Luthor [[FreakyFridayFlip swap bodies]]. In Lionel's body, Clark convinces Ma Kent it's really him by telling the story of how he discovered SuperSpeed at age 6.
** Subverted in "Apocalypse": Clark tries to prove he's a friend to Chloe by revealing some of their past experiences, but since he's in an AlternateUniverse where they have never met, it fails.



* On ''Series/ThirtyRock'', Nathan Lane shows up claiming to be Jack's brother, and Liz is suspicious because Jack has never mentioned a brother and this man pronounces their last name "Dona-hee" as opposed to "Dona-gee." Then he comments that she would be prettier if she didn't scowl, and she knows he's related to [[VitriolicBestBuds Jack]].
* In the first-season finale of ''Series/AgentsOfSHIELD'', Skye convinces Mike she has his son by having Ace repeat what they said to each other in the pilot.
* In an episode of ''Series/SaluteYourShorts'', Camp Anawana is playing a very intense game of CaptureTheFlag with a rival camp. Pinsky ends up going to Donkeylips for help. Donkeylips and Z.Z. aren't sure if he's real or an impostor, so Donkeylips decides to ask him something that he told him earlier in the episode.
-->'''Donkeylips:''' What are the four S's of warfare?\\
'''Pinsky:''' Strength, strategy, and surprise.\\
'''Z.Z.:''' It's Pinsky!\\
'''Donkeylips:''' Shhhh!\\
'''Pinsky:''' That's the fourth S.
* In ''Series/SleepyHollow'', Ichabod and Abbie use a fist-bump to identify each other in Purgatory, as Abbie had recently taught it to Ichabod. Also while in Purgatory, Abbie correctly identifies a Crane imposter since the fake didn't pronounce her title using Crane's insistent British pronunciation: "Lef-tenant".
* In ''Series/JessicaJones2015'', Trish and Jessica decide they need some sort of signal to indicate Jess is not under Kilgrave's mind control. Since Kilgrave would make Jessica pretend like everything's normal, they decide to use a phrase that Jessica [[SomethingTheyWouldNeverSay would never say:]] [[spoiler:"I love you."]]
-->'''Trish:''' You say it, you're still you.
* ''Series/QuantumLeap'': Sam has leaped into an illiterate murderer on the run who is holding a woman and her daughter hostage. He decides to drop the {{masquerade}}, telling her he's a doctor from the future in a TimeTravel experiment. She doesn't believe him. Then he notices her medical textbook, and she reveals that she's in medical school. So he has her quiz him on medical stuff to prove that he's telling the truth. At first she still doesn't believe him, saying that he looked at the book already, so could have memorized the information. Sam quickly fires back: "When was the last time you met an illiterate speed-reader?"
12th Mar '17 5:19:38 PM JamesShade
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* In ''Film/TerminatorGenisys'', when Sarah encounters Future John Connor, she suspects him to be a shapeshifted terminator. Connor gains her trust by citing details of the past that only John Connor would know. [[spoiler: Subverted, it turns out he's a shapeshifted Terminator made from Connor's body]].

to:

* In ''Film/TerminatorGenisys'', when Sarah encounters Future John Connor, she suspects him to be a shapeshifted terminator. Connor gains her trust by citing details of the past that only John Connor would know. [[spoiler: Subverted, it turns out he's a shapeshifted Terminator Terminator-human hybrid made from Connor's body]].
12th Mar '17 5:12:54 PM JamesShade
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* In ''Film/TerminatorGenisys'', when Sarah encounters Future John Connor, she suspects him to be a shapeshifted terminator. Connor gains her trust by citing details of the past that only John Connor would know.

to:

* In ''Film/TerminatorGenisys'', when Sarah encounters Future John Connor, she suspects him to be a shapeshifted terminator. Connor gains her trust by citing details of the past that only John Connor would know. [[spoiler: Subverted, it turns out he's a shapeshifted Terminator made from Connor's body]].
12th Mar '17 8:13:42 AM TonyG
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* ''Disney/{{Aladdin}}'' gives Jasmine the same line, "Do you trust me?", when he's both a street rat and a prince, [[SomethingOnlyTheyWouldSay cluing her in]] to the fact they're the same person. Aladdin didn't intend for that to happen, though, and but he confirms it when he casually mentions Abu.

to:

* ''Disney/{{Aladdin}}'' gives Jasmine the same line, "Do you trust me?", when he's both a street rat and a prince, [[SomethingOnlyTheyWouldSay cluing her in]] to the fact they're the same person. person, and when she casually mentions Abu he absentmindedly confirms it. Aladdin didn't intend for that to happen, though, and but he confirms it when he casually mentions Abu.though.
19th Feb '17 11:11:26 PM GoldenSeals
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->'''Ted''': Okay, wait. If you guys are really us, what number are we thinking of? \\
'''Future Bill and Ted''': 69, dudes! \\
'''Bill and Ted''': Whoa.

to:

->'''Ted''': ->'''Ted:''' Okay, wait. If you guys are really us, what number are we thinking of? \\
'''Future Bill and Ted''': Ted:''' 69, dudes! \\
'''Bill and Ted''': Ted:''' Whoa.



Maybe you claim to be from the future or maybe you say you are some reincarnation. Whatever it may be, Mr. Suspicious isn't buying it. So what do you do? You tell or show him the one thing that absolutely proves your claim beyond a shadow of a doubt.

Can be PlayedForLaughs if the suspicious person doesn't accept a series of complex and personal things that should prove the other person's identity, only to take something like 'Your favourite colour is red' as irrefutable proof.

A subtrope of GodTest. Compare CovertDistressCode, SomethingOnlyTheyWouldSay and OnlyTheKnowledgableMayPass. May be in SpySpeak if it's a sign/countersign challenge.

CrazyPrepared characters naturally have at least one of these.

See also TwoHalvesMakeAPlot: an everyday object - a business card, a dollar bill, a coin, a plastic token, etc - that has been torn/broken in half as a means of identification; As it's extremely unlikely that another broken object will match up with either piece, it can be used as a relatively secure equivalent of a trust password. Just be sure whoever you give it to can hang on to it.

Not at all related to SafeWord. [[ConvenientlyCommonKink Usually.]]

to:

A character needs to prove his identity or situation to another character who's not likely to believe him. Maybe you claim to be he's [[TimeTravel from the future]], or he's [[{{Reincarnation}} some other character reincarnated]]. Maybe he has to pass a GodTest. He might even have to prove his identity to his past or future or maybe you say you are some reincarnation. Whatever it may be, Mr. Suspicious isn't buying it. So what do you do? You tell or show him self. That's when he breaks out the one thing Trust Password -- something that absolutely proves your claim will prove his identity beyond a shadow of a doubt.

Can Trust Passwords come in several forms. Very often, it will be SomethingOnlyTheyWouldSay. It can be set up in advance as a CovertDistressCode or a form of SpySpeak (often in sign/countersign form). It could be [[OnlyTheKnowledgableMayPass specialized knowledge of certain facts or events]]. Or it could be an object that has a special significance (such as [[TwoHalvesMakeAPlot an object that's been separated in half]], so if you have one half only someone you trust has the other).

The trope can
be PlayedForLaughs if quite easily -- the suspicious person doesn't accept a series of complex and personal things skeptical character might not believe an otherwise airtight password, or the password might be common knowledge such that should prove anyone can easily impersonate the other person's identity, only to take something like 'Your favourite colour is red' as irrefutable proof.

A subtrope of GodTest. Compare CovertDistressCode, SomethingOnlyTheyWouldSay and OnlyTheKnowledgableMayPass. May be in SpySpeak if
character.

And
it's a sign/countersign challenge.

CrazyPrepared characters naturally have at least one of these.

See also TwoHalvesMakeAPlot: an everyday object - a business card, a dollar bill, a coin, a plastic token, etc - that has been torn/broken in half as a means of identification; As it's extremely unlikely that another broken object will match up with either piece, it can be used as a relatively secure equivalent of a trust password. Just be sure whoever you give it to can hang on to it.

Not at all
not related to SafeWord. [[ConvenientlyCommonKink Usually.]]
(Usually.)]]



* A Tim Horton's commercial had two Canadians crossing the border, with proof of identity given by the "R-R-Roll up the R-R-Rim to Win" slogan. The next two in line mispronounced it.

to:

* A Tim Horton's commercial had two Canadians people crossing the border, with proof of identity given border into Canada proving that they're true Canadians by showing that they know how to correctly pronounce the "R-R-Roll chain's big yearly promotion: "[[TrrrillingRrrs R-R-Roll up the R-R-Rim to Win" slogan. Win!]]" The next two in line mispronounced can't do it.



* In the fourth ''LightNovel/HaruhiSuzumiya'' novel, Kyon finds himself in an alternate universe where the SOS members are ordinary humans. Haruhi won't even give him the time of day until [[spoiler:he desperately introduces himself as John Smith, the alias he had used as a time traveller helping her out three years ago. Once the world is returned to 'normal', he keeps this as a trump card (emergency use only!) to [[CrowningMomentOfAwesome blackmail Yuki's boss]]]].
** Previously played straight in ''Bamboo Leaf Rhapsody'': after [[spoiler:Kyon hands over to Yuki the paper piece she will give him in three years time (he's time traveling at the moment) she is convinced enough to synchronize (sharing memories with her future self, effectively making her current self and Yuki in three years time the same person)]]. Inverted immediately after when [[spoiler: Yuki takes her glasses off, showing a habit she will take by Kyon's request in three years time]].
** Played with multiple times in a different context. [[spoiler: Adult Mikuru tries to use a distinctive mole on one breast to convince Kyon of who she is the first time they meet, only to realize that Kyon hasn't actually seen the mole on Younger Mikuru yet. Much later, Kyon uses the lack of a mole to realize that the Mikuru in his room is a fake]].
*** Probably worth mentioning [[spoiler:that Kyon then proceeded to tell Younger Mikuru about the mole, which she didn't know about yet, which is how she finds out about it in the first place, [[StableTimeLoop but that's a different trope]].]]
*** And in ''Disappearance'', [[spoiler:attempting to use this on an alternate universe Mikuru utterly fails, and gets him labeled a pervert and punched out by Mikuru, of all people]].
* Yusuke of ''Manga/YuYuHakusho'' regrets not having one of these when he possesses Kuwabara, and not a single person believes he's actually Yusuke. He ends up identifying himself to Keiko by grabbing her breasts (or, in the edited-for-TV version, peeking up her skirt), which elicits a reflex response of "Yusuke you jerk!" and a slap, at which point she finally accepts that it's him. And it was unnecessary because she recognizes his body language. Oh well.
* [[PlayingWithATrope Played with]] in ''{{Manga/Naruto}}''. Sasuke Uchiha, having just defeated an imposter through recognizing him by luck, gives one to both Sakura and Naruto to say. However, he knew that the real Naruto wouldn't be able to remember it, and (correctly) identifies another imposter based on this several minutes later.
* In a filler episode of ''Anime/GhostInTheShellStandAloneComplex'', a terrorist known as "Angel's Wing" ("Angel Feathers" in the English dub) gives one of these to [[spoiler:his blind, wheelchair-bound daughter]] so that she'll know it's him even if she doesn't recognize him. At the end of the episode, [[spoiler: Angel's Wing is captured in a chapel... Right before his daughter enters. She then says her half of the password ("What is the angel planning to do today?") At first, it seems as if Batou, who had heard ''both'' halves of the password earlier, is going to say the second half (something like "The angel will rain feathers down from the heavens") if only to make the girl happy, but he doesn't, changing it to ("the angel... isn't planning to go anywhere")]].
** One of the final episodes in 2nd Gig has the BigBad trying to send Rangers after Section 9. [[spoiler: They immediately stand down after running into Batou, a former Ranger; something they can immediately tell because all Rangers have the exact same ElectronicEyes.]]

to:

* In This occurs frequently in the fourth ''LightNovel/HaruhiSuzumiya'' series:
** In ''Bamboo Leaf Rhapsody'', Kyon [[spoiler:gives Yuki the piece of paper that she gives him in three years' time as he travels through time himself.]] This convinces her to [[spoiler:synchronize her memories with her future self, effectively merging her current and future selves into the same person]]. And then she returns the favor immediately afterward, [[spoiler:taking off her glasses the same way she does three years later]].
** In the fourth light
novel, Kyon finds himself in an alternate universe AlternateUniverse where the SOS members are ordinary humans. Haruhi won't even give him the time of day day, until [[spoiler:he desperately introduces in desperation, he [[spoiler:introduces himself as John Smith, the alias he had used as a time traveller traveler helping her him out three years ago. Once the ago.]] After he does that and [[spoiler:the world is returned to 'normal', "normal"]], he keeps this as a an emergency trump card (emergency use only!) and [[spoiler:finds himself using it to [[CrowningMomentOfAwesome blackmail Yuki's boss]]]].
** Previously played straight in ''Bamboo Leaf Rhapsody'': after [[spoiler:Kyon hands over to Yuki the paper piece she will give him in three years time (he's time traveling at the moment) she is convinced enough to synchronize (sharing memories with her future self, effectively making her current self and Yuki in three years time the same person)]]. Inverted immediately after when [[spoiler: Yuki takes her glasses off, showing a habit she will take by Kyon's request in three years time]].
** Played with multiple times in a different context. [[spoiler:
Adult Mikuru tries to use convinces Kyon of her identity by [[spoiler:showing him a distinctive mole on one her breast to convince -- except Kyon of who she is the first time they meet, only to realize that Kyon hasn't actually seen the mole on Younger Mikuru yet. Much later, Kyon uses the lack of a mole to realize that the Mikuru in his room is a fake]].
*** Probably worth mentioning [[spoiler:that Kyon then proceeded to tell Younger Mikuru about the mole, which she
didn't know about that yet, which is how she finds even though Mikuru claims he pointed it out about it in the first place, [[StableTimeLoop but that's a different trope]].]]
*** And in ''Disappearance'', [[spoiler:attempting
to use her.]] Kyon uses this on information to [[spoiler:point this fact out to the younger Mikuru, turning the whole thing into a StableTimeLoop.]] It pops up later, too -- he recognizes [[spoiler:a fake Mikuru because she doesn't have the mole]], and he tries it again in ''Disappearance'' [[spoiler:on an alternate universe Mikuru utterly fails, and gets Mikuru, who calls him labeled a pervert and punched out by Mikuru, of all people]].
punches him out]].
* In ''Manga/YuYuHakusho'', Yusuke of ''Manga/YuYuHakusho'' regrets not having one of these when he possesses Kuwabara, Kuwabara to try and not a single person believes tell Keiko that he's actually Yusuke. He ends trying to come back to life and needs his body. She doesn't believe him, and he tries to come up identifying himself to Keiko by grabbing with a Trust Password. So he gropes her breasts (or, (or in the edited-for-TV version, peeking [[{{Bowdlerize}} TV version]], peeks up her skirt), which elicits a reflex response of "Yusuke causing her to reflexively slap him and yell "Yusuke, you jerk!" and a slap, at which point And in the end, she finally accepts tells him that it's him. And it was unnecessary because after all -- she recognizes recognized his body language. Oh well.
language.
* ''Manga/{{Naruto}}'' [[PlayingWithATrope Played plays with]] in ''{{Manga/Naruto}}''. the trope. Sasuke Uchiha, having just defeated an imposter through impostor by recognizing him by through sheer luck, gives one has enough of a scare to both give Trust Passwords to Sakura and Naruto. But in Naruto's case, the password is so complicated that he knows [[IdiotHero Naruto to say. However, he knew that the real Naruto wouldn't be able to will never remember it, it]] -- so when an impostor impersonating Naruto shows up and (correctly) identifies another imposter based on this several minutes later.
correctly recites the password, he knows it's a fake.
* In a filler episode of ''Anime/GhostInTheShellStandAloneComplex'', a ''Anime/GhostInTheShellStandAloneComplex'':
** A
terrorist known as "Angel's Wing" ("Angel (or "Angel Feathers" in the English dub) gives one of these a Trust Password to [[spoiler:his blind, wheelchair-bound daughter]] so that she'll know it's him even if she doesn't recognize him. it. At the end of the episode, [[spoiler: Angel's Wing is captured he finds himself [[spoiler:captured in a chapel... Right before chapel, when his daughter enters. happens to enter. She then says gives her half of the password ("What is the angel planning to do today?") At first, it seems as if Batou, who had heard ''both'' Batou knows both halves of the password earlier, is going to say password, and he could give the second half (something like "The angel will rain feathers down from the heavens") if right response (if only to make the girl happy, her happy), but he doesn't, changing it to ("the doesn't -- he tells her, "The angel... isn't planning to go anywhere")]].
anywhere."]]
** One of the final episodes in 2nd Gig has the BigBad trying to send Rangers after Section 9. [[spoiler: They [[spoiler:They immediately stand down after running into Batou, a former Ranger; something they can tell this immediately tell because all Rangers have the exact same ElectronicEyes.]]



** After learning that one of the villain's lackeys can duplicate appearances, Zoro comes up with a solution; To distinguish each other, each Straw Hat should wear a white cloth over their arm [[spoiler: to hide the ''true'' trust sign...an X]].
** In the Dressrosa arc, Luffy is reunited with someone he had thought long dead. Said individual starts ask about the time they stole Dadan's liquor to confirm his identity but Luffy is glomping him in joy before he can finish the sentence.
* ''LightNovel/AllYouNeedIsKill'' has a variant. Rita is part of a controlled timeloop; after every battle, she is sent back in time one day to improve the outcome the next time around. Every battle, she asks everyone she can the same weird question (a different one every battle), like "Is it true that in Japan green tea is complimentary after a meal?" That way, if another looper ever shows up, they can prove their identity simply by answering the question before the battle even starts.
* In ''VisualNovel/SteinsGate'', Makise Kurisu provides a trust password (My Fork) to Okabe to convince her past self that he came from future using technology she finished building a few minutes ago. Humorously, the password she uses is a very old 2ch meme roughly meaning "lover", so past-Kurisu is horrified when Okabe uses it (fortunately for her, Okabe doesn't seem to know its meaning).
-->'''Okabe''': What you want most right now is "My Fork"!\\
'''Kurisu''': [[BigWhat WHAT!?]]\\
'''Okabe''': You already have "My Spoon", apparently.\\
'''Kurisu''': I am going to ''kill'' my future self five hours from now...
* In ''LightNovel/MushokuTensei'' [[spoiler:future Rudeus]] convinces Rudeus of his identity, and thus to trust his warnings, by saying something only he could know: [[spoiler:[[NoNameGiven Their Japanese name]]]].
* [[spoiler: Gilthunder's supposed BadassBoast]] in [[Manga.NanatsuNoTaizai The Seven Deadly Sins]] turns out to be this. It's a phrase learned from Meliodas, to be used if they're ever in deep trouble.
-->[[spoiler:'''Gilthunder''': I am now stronger than any of the Seven Deadly Sins!]]

to:

** After learning that one of the villain's lackeys can duplicate appearances, Zoro comes up with a solution; To distinguish each other, solution: each Straw Hat should wear a white cloth over their arm [[spoiler: to [[spoiler:to hide the ''true'' trust sign...sign, an X]].
** In the Dressrosa arc, Luffy is reunited with someone he had thought long dead. Said individual starts ask asking about the time they stole Dadan's liquor to confirm his identity identity, but Luffy is [[TheGlomp glomping him him]] in joy before he can finish the sentence.
* ''LightNovel/AllYouNeedIsKill'' has a variant. Rita is part of a controlled timeloop; time loop; after every battle, [[GroundhogPeggySue she is sent back in time one day day]] to improve the outcome the next time around. Every battle, she asks everyone she can the same weird question (a different one every battle), like "Is it true that in Japan green tea is complimentary after a meal?" That way, if another looper ever shows up, they can prove their identity simply by answering the question before the battle even starts.
* In ''VisualNovel/SteinsGate'', Makise Kurisu provides Okabe a trust password (My Fork) to Okabe ("My Fork") to convince her past self that he came from future using technology she finished building a few minutes ago. Humorously, the password she uses is a very old [[ImageBoards 2ch meme meme]] roughly meaning "lover", so past-Kurisu is horrified when Okabe uses it (fortunately for her, Okabe doesn't seem to know its meaning).
-->'''Okabe''':
recognize the meme).
-->'''Okabe:'''
What you want most right now is "My Fork"!\\
'''Kurisu''': '''Kurisu:''' [[BigWhat WHAT!?]]\\
'''Okabe''': '''Okabe:''' You already have "My Spoon", apparently.\\
'''Kurisu''': '''Kurisu:''' I am going to ''kill'' my future self five hours from now...
* In ''LightNovel/MushokuTensei'' [[spoiler:future Rudeus]] convinces Rudeus of his identity, and thus to trust his warnings, by saying something only he could know: [[spoiler:[[NoNameGiven Their their Japanese name]]]].
* In ''[[Manga.NanatsuNoTaizai The Seven Deadly Sins]]'', [[spoiler: Gilthunder's supposed BadassBoast]] in [[Manga.NanatsuNoTaizai The Seven Deadly Sins]] turns out to be this.a trust password. It's a phrase learned from Meliodas, to be used if they're ever in deep trouble.
-->[[spoiler:'''Gilthunder''': -->[[spoiler:'''Gilthunder:''' I am now stronger than any of the Seven Deadly Sins!]]



* During ''ComicBook/TheDeathOfSuperman'' storyline, the real Franchise/{{Superman}} proves himself to Lois with Clark Kent's favorite movie: [[spoiler: ''Film/ToKillAMockingbird'']].
* In later comics, Superman's codeword to Lois is "Beef bourguignon with ketchup". Though in this case, it's a way to let Lois know through an intermediary that he's safe. A farming tradition. Subverted when Parasite poses as Lois and is able to use the password.
* During the Obsidian Age arc in the ''Franchise/JusticeLeagueOfAmerica'', in which the entire League is killed and their souls trapped by an ancient Atlantean sorceress, it's revealed that {{Franchise/Batman}}'s passcode for ComicBook/{{Nightwing}} is "The Daring Young Man on the Flying Trapeze"; a reference of course to Dick Grayson's boyhood career. Also, song lyrics.
* ''ComicBook/MortadeloYFilemon'': They have an [[SparseListOfRules arbitrarily catalogued]] amount of them. A RunningGag is said password be very offensive to some group or collective that happens to be within earshot. [[HilarityEnsues A beating ensues]].
** One particularly extreme password was reciting DonQuixote ''in its entirety''. After unsuccessfully trying to convince the guard on the other side of the door to skip the password for once, Filemón just starts reciting aloud the whole book, [[PhotographicMemory which he proves to know by heart]]. Time passes, it rains, Filemón grows a beard, and right before he's done reciting the book, the door collapses. When Mortadelo and Filemón enter the building while shaving their beards, they notice the guard has died of old age.

to:

* During ''ComicBook/TheDeathOfSuperman'' storyline, From ''Franchise/{{Superman}}'' comics:
** In ''ComicBook/TheDeathOfSuperman'',
the real Franchise/{{Superman}} Superman proves himself his identity to Lois with by naming Clark Kent's favorite movie: [[spoiler: ''Film/ToKillAMockingbird'']].
*
movie, [[spoiler:''Film/ToKillAMockingbird''.]]
**
In later comics, Superman's codeword to Lois is Superman sets up a code phrase with Lois: "Beef bourguignon with ketchup". Though in this case, it's a way ketchup" (a farming tradition). He uses it to let Lois know through an intermediary that he's safe. A farming tradition. Subverted safe even when he can't contact her directly. Unfortunately, Parasite poses as Lois and is also able to use the password.
password when posing as Lois.
* ''Franchise/JusticeLeagueOfAmerica'': During the Obsidian Age arc in the ''Franchise/JusticeLeagueOfAmerica'', arc, in which the entire League is killed and their souls trapped by an ancient Atlantean sorceress, it's revealed that {{Franchise/Batman}}'s Franchise/{{Batman}}'s passcode for ComicBook/{{Nightwing}} is "The Daring Young Man on the Flying Trapeze"; a reference of course not only are they song lyrics, but they also refer to Dick Grayson's boyhood career. Also, song lyrics.
career.
* ''ComicBook/MortadeloYFilemon'': They ''ComicBook/MortadeloYFilemon'' have an [[SparseListOfRules arbitrarily catalogued]] amount number of them. trust passwords. A RunningGag is said for the password to be very offensive to some group or collective that happens to be within earshot. [[HilarityEnsues A beating ensues]].
** One particularly extreme password was reciting DonQuixote ''in ''Literature/DonQuixote'' in its entirety''. After entirety. Filemón tries unsuccessfully trying to convince the guard on the other side of the door to let him skip the password for once, Filemón just starts reciting aloud once. He has a PhotographicMemory and knows it by heart, but by the whole book, [[PhotographicMemory which he proves to know by heart]]. Time passes, it rains, Filemón grows a beard, and right before time he's done finished reciting the book, it, he's grown a TimePassageBeard. And then the door collapses. When Mortadelo collapses, and Filemón enter the building while shaving their beards, they notice the guard has turns out to have died of old age.



** Used by GenreSavvy players in the comics. Often, players will set up a "Doppleganger Password"; should a character become separated from the group and later rejoin, they can be asked to provide the password in order to prove that they're not an infiltrator in disguise.
** Used to great effect by the Black Hands group. During an [[SeriousBusiness annual Hackmaster tournament]], Newt asks Stevil for the password and, not getting it, peppers his body with crossbow bolts and dumps his body down a well. All to the good, except that Newt accidentally (or [[JerkAss "accidentally"]]) forgot to set up the password with Stevil ahead of time, giving him an excuse to take him out of the game. [[DrillSergeantNasty Nitro]] doesn't buy the excuse and, when the Black Hands are eliminated, orders Newt to his house for "remedial training". And to bring a sack lunch.

to:

** Used by GenreSavvy players in the comics. Often, players will set up a "Doppleganger "Doppelganger Password"; should a character become separated from the group and later rejoin, they can be asked to provide the password in order to prove that they're not an infiltrator in disguise.
** Used It's used to great effect by the Black Hands group. During an [[SeriousBusiness annual Hackmaster tournament]], Newt asks Stevil for the password and, not getting it, peppers his body with crossbow bolts and dumps his body down a well. All to the good, except that Newt accidentally (or [[JerkAss "accidentally"]]) forgot to set up the password with Stevil ahead of time, giving him an excuse to take him out of the game. [[DrillSergeantNasty Nitro]] doesn't buy the excuse and, when the Black Hands are eliminated, orders Newt to his house for "remedial training". And to bring a sack lunch.



* Ed and Sam of qntm's [[http://qntm.org/?ed Ed Stories]] both have time travel passwords, for use when they need to prove their identities to themselves. They make use of these passwords in [[http://qntm.org/?beherenow4 Be Here Now: 4 of 5.]]

to:

* Ed and Sam of qntm's [[http://qntm.''[[http://qntm.org/?ed Ed Stories]] Stories]]'' both have time travel passwords, for use when they need to prove their identities to themselves. They make use of these passwords in [[http://qntm.''[[http://qntm.org/?beherenow4 Be Here Now: 4 of 5.]]]]''



* In the ''Manga/{{Bleach}}'' fic ''Fanfic/HogyokuExMachina'', Yamamoto gives Ichigo one of these to prepare for when Rukia will be [[RetGone Ret Goned]] in the future [[NonSerialMovie (i.e. the third film)]]. [[spoiler: It also ends up being useful for identification against [[BigBad Aizen's]] [[MasterOfIllusion illusions]], though Ichigo almost gets killed then anyway since the password is a name and he has trouble remembering it]].

to:

* In the ''Manga/{{Bleach}}'' fic ''Fanfic/HogyokuExMachina'', ''Fanfic/HogyokuExMachina'':
**
Yamamoto gives Ichigo one of these to prepare for when Rukia will be [[RetGone Ret Goned]] turn RetGone in the future [[NonSerialMovie (i.(''i.e. '' [[NonSerialMovie the third film)]]. film]]). [[spoiler: It also ends up being useful for identification against [[BigBad Aizen's]] [[MasterOfIllusion illusions]], though Ichigo almost gets killed then anyway since the password is a name and he still has trouble remembering to scramble as he struggles to remember it]].



* ''Fanfic/WinterWar'': How do you convince someone who's been [[MasterOfIllusion Aizen's]] prisoner for ''months'' that you really are you? [[spoiler: You hand him his [[EmpathicWeapon zanpakutou]]- which will do the convincing for you]].

to:

* ''Fanfic/WinterWar'': How do you convince someone who's been [[MasterOfIllusion Aizen's]] prisoner for ''months'' that you really are you? [[spoiler: You [[spoiler:You hand him his [[EmpathicWeapon zanpakutou]]- zanpakutou]], which will do the convincing for you]].



* In the ''[[Fanfic/EakinsHardReset Hard Reset]]'' sequel ''[[http://www.fimfiction.net/story/145711/hard-reset-2-reset-harder Hard Reset 2: Reset Harder]]'', when Celestia hears that Twilight is a fellow [[GroundhogDayLoop time looper]], she tells Twilight a password to unlock secret knowledge in Celestia's brain. When Twilight repeats the password to Celestia later on, [[spoiler:she's paralyzed by a powerful spell, and Celestia immediately kills her after revealing that the "secret knowledge" is the rest of the password. It's repeating the ENTIRE combination that convinces Celestia of Twilight's story]].
* In ''[[http://tvtropes.org/pmwiki/pmwiki.php/FanFic/Sols06sPhineasAndFerbVerse PnF: Stolen Identity]]'', Phineas does an impromptu one on [[EvilTwin Ferb's replacement]], asking him about the day they first met. Different from the typical example in that the first time he asks this question, he doesn't realize he's talking to an impostor (rather he thinks Ferb's gone mad) and wants reassurance that Ferb is still the person he loves. Later the real Ferb answers the question (Phineas insisted on saving Ferb some cake if you're wondering) much to Phineas' obvious relief.
* In the ''Fanfic/UnacceptableSitchSeries'' (specifically "Under the Milky Way Tonight"), Señor Senior, Sr, gave his attorneys a list of passwords to prove he was of sound mind and free of coercion. Specifically, any future changes to his will would include all but one of them.
* Played for laughs in ''Fanfic/TheWrongReflection''. Tess randomly demands of Eleya at gunpoint why Tess joined Starfleet, to make sure Dal Kanril hasn't tried to replace her. After going "WTF?" Eleya answers, and then asks Tess if she really thought Eleya wasn't herself.

to:

* In the ''[[Fanfic/EakinsHardReset Hard Reset]]'' sequel ''[[http://www.fimfiction.net/story/145711/hard-reset-2-reset-harder Hard Reset 2: Reset Harder]]'', when Celestia hears that Twilight is a fellow [[GroundhogDayLoop time looper]], she tells Twilight a password to unlock secret knowledge in Celestia's brain. When Twilight repeats the password to Celestia later on, [[spoiler:she's paralyzed by a powerful spell, and Celestia immediately kills her after revealing that the "secret knowledge" is the rest of the password. It's repeating the ENTIRE ''entire'' combination that convinces Celestia of Twilight's story]].
* In ''[[http://tvtropes.org/pmwiki/pmwiki.php/FanFic/Sols06sPhineasAndFerbVerse PnF: Stolen Identity]]'', Phineas does an impromptu one on [[EvilTwin Ferb's replacement]], asking him about the day they first met. Different It's different from the typical example in that the first time he asks this question, he doesn't realize he's talking to an impostor (rather he thinks Ferb's gone mad) and wants reassurance that Ferb is still the person he loves. Later the real Ferb answers the question correctly (Phineas insisted on saving Ferb some cake if you're wondering) cake), much to Phineas' obvious relief.
* In the ''Fanfic/UnacceptableSitchSeries'' (specifically "Under the Milky Way Tonight"), Señor Senior, Sr, Sr. gave his attorneys a list of passwords to prove he was of sound mind and free of coercion. Specifically, any future changes to his will would include all but one of them.
* Played for laughs in ''Fanfic/TheWrongReflection''. ''Fanfic/TheWrongReflection'': Tess randomly demands of Eleya at gunpoint why Tess joined Starfleet, to make sure Dal Kanril hasn't tried to replace her. After going "WTF?" Eleya answers, and then asks Tess if she really thought Eleya wasn't herself.



* In ''[[https://www.fanfiction.net/s/6439871/1/A-Different-Halloween A Different Halloween]]'' if Lily Potter uses the word "darling" at the start of a phone conversation with James it means that she's safe and coercion-free.
* ''FanFic/DiariesOfAMadman'': Navarone, when dealing with shapeshifters alongside his adopted daughter Taya, gives her a few of these for verification. [[spoiler: He also has his true name, which ostensibly isn't accurately recorded in his journals, replaced instead with 'Anonymous'.]]
* The {{WebAnimation/RWBY}} fanfic ''FanFic/FourDeadlySecrets'' has [[spoiler:Neo]] and [[spoiler:Ruby]] exchange one, in the [[SpySpeak form of sign/counter-sign]] when they first meet.
-->'''[[spoiler:Neo]]''': So breathe easy, sister. \\
'''[[spoiler:Ruby]]''': Free air is easy to breathe, sister.
* ''Fanfic/TheBridge'': Gigan is unsure if the being he's talking to is Monster X or [[SuperPoweredEvilSide Kaizer Ghidorah]] and asks him to tell him two things only his best friend would know. X proves himself by talking about how the two of them stopped the [[NoodleIncident radio incident with the Kilaaks]] and what Gigan did the moment they first met. Also the fact that X calls Gigan his best friend while Kaizer would never do that as he hates everyone.
* ''[[http://archiveofourown.org/series/82162 Stars From Home]]'': When Hank's cure first works, Scott assumes the not-blue-and-furry Hank is a imposter. Hank tries twice before managing to convince Scott of who he is--because he knows why Scott doesn't like The Andy Griffith Show. A few chapters later, Charles has to prove his identity to Ruth when he uses Hank's serum to walk. His initial attempt at using personal details does not go well.

to:

* In ''[[https://www.fanfiction.net/s/6439871/1/A-Different-Halloween A Different Halloween]]'' Halloween]]'', if Lily Potter uses the word "darling" at the start of a phone conversation with James James, it means that she's safe and coercion-free.
* ''FanFic/DiariesOfAMadman'': Navarone, when dealing with shapeshifters alongside his adopted daughter Taya, gives her a few of these for verification. [[spoiler: He [[spoiler:He also has his true name, which ostensibly isn't accurately recorded in his journals, replaced instead with 'Anonymous'."Anonymous".]]
* The {{WebAnimation/RWBY}} ''{{WebAnimation/RWBY}}'' fanfic ''FanFic/FourDeadlySecrets'' has [[spoiler:Neo]] [[spoiler:Neo and [[spoiler:Ruby]] spoiler:Ruby]] exchange one, in the [[SpySpeak form of sign/counter-sign]] when they first meet.
-->'''[[spoiler:Neo]]''': -->'''[[spoiler:Neo]]:''' So breathe easy, sister. sister.\\
'''[[spoiler:Ruby]]''': '''[[spoiler:Ruby]]:''' Free air is easy to breathe, sister.
* ''Fanfic/TheBridge'': Gigan is unsure if the being he's talking to is Monster X or [[SuperPoweredEvilSide Kaizer Ghidorah]] and asks him to tell him two things only his best friend would know. X proves himself by talking about how the two of them stopped the [[NoodleIncident radio incident with the Kilaaks]] and what Gigan did the moment they first met. Also the fact that And X calls Gigan his best friend friend, while Kaizer would never do that as because he hates everyone.
HatesEveryoneEqually.
* ''[[http://archiveofourown.org/series/82162 Stars From Home]]'': Home]]'':
**
When Hank's cure first works, Scott assumes the not-blue-and-furry Hank is a imposter. Hank tries twice before managing to convince Scott of who he is--because is -- because he knows why Scott doesn't like The Andy Griffith Show. ''Series/TheAndyGriffithShow''.
**
A few chapters later, Charles has to prove his identity to Ruth when he uses Hank's serum to walk. His initial attempt at using personal details does not go well.



-->'''Nami''': Who is the second greatest traveler in the world?
-->'''Cross''': That would be [[MythologyGag Pandaman]], ranking right below Gol D. Roger!
-->'''Nami''': Wrong answer! Pandaman doesn't exist.
-->'''Cross''': ''That's a lie!'' Pandaman is real, just like the great [[Creator/EiichiroOda Goda]]!

to:

-->'''Nami''': -->'''Nami:''' Who is the second greatest traveler in the world?
-->'''Cross''':
world?\\
'''Cross:'''
That would be [[MythologyGag Pandaman]], ranking right below Gol D. Roger!
-->'''Nami''':
Roger!\\
'''Nami:'''
Wrong answer! Pandaman doesn't exist.
-->'''Cross''':
exist.\\
'''Cross:'''
''That's a lie!'' Pandaman is real, just like the great [[Creator/EiichiroOda Goda]]!



* ''Disney/{{Aladdin}}'', with "Do you trust me?", which works both when he's a street rat and a prince, which also starts to [[SomethingOnlyTheyWouldSay show]] that they're the same person. This was partly accidental -- Aladdin didn't intend to reveal his true identity to Jasmine, but she came to suspect they were one and the same, [[spoiler:[[BluffTheImpostor then confirmed it by casually mentioning Abu later on]]]].

to:

* ''Disney/{{Aladdin}}'', with ''Disney/{{Aladdin}}'' gives Jasmine the same line, "Do you trust me?", which works both when he's both a street rat and a prince, which also starts to [[SomethingOnlyTheyWouldSay show]] that cluing her in]] to the fact they're the same person. This was partly accidental -- Aladdin didn't intend for that to reveal his true identity to Jasmine, happen, though, and but she came to suspect they were one and the same, [[spoiler:[[BluffTheImpostor then confirmed he confirms it by when he casually mentioning Abu later on]]]].mentions Abu.



* ''Film/BillAndTedsExcellentAdventure'' has the future selves prove that they are who they are by identifying what number the present selves are thinking of.

to:

* ''Film/BillAndTedsExcellentAdventure'' ''Film/BillAndTedsExcellentAdventure'':
** The first film
has the protagonists' future selves prove that they are who they are by identifying what number the present selves are thinking of.their identities thusly:



** Double subverted in the sequel; when the heroes' {{Evil Twin}}s arrive, Ted is suspicious, but Bill convinces him to trust them. Then Ted trusts his robot counterpart after it passes a HowManyFingers test.
* Turned on its head in ''Film/BillAndTedsBogusJourney'' when the "Evil Robot Usses" correctly guess how many fingers Ted is going to show them; it's entirely possible he only held up the amount they said because they said it.

to:

** Double subverted in In ''Film/BillAndTedsBogusJourney'', Ted tries this on the sequel; when the heroes' {{Evil Twin}}s arrive, Ted is suspicious, but Bill convinces him to trust them. Then Ted trusts his boys' [[EvilTwin "evil robot counterpart after it passes usses"]] by giving them a HowManyFingers test.
* Turned on its head in ''Film/BillAndTedsBogusJourney'' when the "Evil Robot Usses" correctly guess how many
test. They pass, although since Ted was hoping for them to pass, he may just have flashed whatever number of fingers Ted is going to show them; it's entirely possible he only held up the amount they said because they said it.he was holding



** 2015 Biff Tannen demonstrates to his 1955 self that he and his Sports Almanac really are from the future by predicting an extreme long shot football game result in ''Film/BackToTheFuturePartII''. Although Old Biff makes a point of not telling his younger self who he really is, he demonstrates knowledge that only Young Biff would have, such as how to start his car.
** From the [[Film/BackToTheFuture first film]], Doc will not believe Marty is a teenager from the future until Marty proves it. Marty first tries to validate himself by revealing "future" history, which Doc laughs off because he refuses to believe that [[ItWillNeverCatchOn Hollywood actor Ronald Reagan could possibly ever become President]]. Doc only believes Marty when the latter mentions things he could know only from Doc himself, particularly Doc's accident and vision that later led to the creation of the time machine itself.
* Similarly, the protagonist of ''Film/{{Frequency}}'' convinces his father in the past that he really is speaking from the future by detailing a baseball game that hadn't happened yet. Protagonist Sr. buys it when he sees the game happen exactly as described the next day.
* Subverted in ''Film/GhostTown''. Ricky Gervais' character has started telling the wife of a dead husband (whose ghost he can see) facts that he shouldn't know. So she makes him prove that Ricky's really talking to the husband with a recurring nightmare the husband had that he only told her about. [[spoiler: He says drowning, but it turns out that's way off, and the husband was purposely lying to Ricky so that he would stay away from the wife.]]

to:

** 2015 Biff Tannen demonstrates to his 1955 self that he and his Sports Almanac really are from the future by predicting an extreme long shot football game result in ''Film/BackToTheFuturePartII''. Although Old Biff makes a point of not telling his younger self who he really is, he demonstrates knowledge that only Young Biff would have, such as how to start his car.
** From the
In [[Film/BackToTheFuture the first film]], Doc will not believe Marty is a teenager tries to convince 1955 Doc that he's from the future until Marty proves it. Marty and he needs Doc's help. He first tries to validate himself by revealing reveal "future" history, which Doc laughs off because he refuses to believe that [[ItWillNeverCatchOn Hollywood actor Ronald Reagan could possibly ever become is really President]]. Doc only believes Marty when the latter mentions things he could successfully gets Doc to believe him by telling him something only Doc would know only from Doc himself, particularly Doc's accident and -- the vision that later led to the creation his invention of the time machine itself.
machine.
** In ''Film/BackToTheFuturePartII'', 2015 Biff doesn't actually want his 1955 self to recognize him, but he does get his past self to trust him and take the Sports Almanac by demonstrating knowledge only young Biff would have, such as how to start his car.
* Similarly, In ''Film/{{Frequency}}'', the protagonist of ''Film/{{Frequency}}'' convinces his father in the past that he he's really is speaking from the future by detailing a baseball game that hadn't happened hasn't happen yet. Protagonist Sr. buys it when he When the father sees the game the next day happen exactly as described the next day.
described, he believes.
* Subverted in ''Film/GhostTown''. Ricky Gervais' character has started telling the wife of a dead husband (whose ghost he can see) facts that he shouldn't know. So she makes him prove that Ricky's really talking to the husband with a recurring nightmare the husband had that he only told her about. [[spoiler: He [[spoiler:He says drowning, but it turns out that's way off, and the husband was purposely lying to Ricky so that he would stay away from the wife.]]



** ''Film/XMen1'': After being fooled by [[Characters/XMenFilmSeriesMystique Mystique]] one too many times, Cyclops demands that Wolverine prove he is who he says he is, under threat of being eye-beamed. Wolverine's response: "You're a dick." It works.
** ''Film/XMenDaysOfFuturePast'': Logan convinces 1973 Charles to hear him out by telling him some details about his childhood that he learned from future Charles and that the younger Xavier hadn't told anyone up until this point in time.
--->'''Logan''': I know your powers came when you were nine. I know you thought you were going crazy when it started, all the voices in your head, and it wasn't until you were twelve that you realized all the voices were in everyone else's head.
* In ''Film/{{Cooperstown}}'', a former baseball player claims to be seeing the ghost of his deceased friend. To figure out if he's lying or not, another character asks him several questions that she thinks Harry won't know, but that the ghost would know. As it turns out, [[spoiler: Harry was seeing the ghost of his friend. The questions proved it]].
* ''Film/StarTrek'' actually gives an example where this doesn't work. Spock Prime greets Kirk with [[Film/StarTrekIITheWrathOfKhan "I have been and always shall be your friend"]]. Except Kirk and Spock aren't friends yet in this timeline, so it kind of falls flat. He finally resorts to using a [[ExpositionBeam mindmeld]] instead.
* In ''Film/TwelveMonkeys'', Cole can't figure out if he's actually from the future or if he's just crazy. He figures it out when [[spoiler: he tells Kathryn to make a phone call for him to a phone he knows will be monitored in the future. Kathryn leaves the message Cole had been told about in the future, which confirms he's from the future]].
* From ''Film/YouOnlyLiveTwice'':
--> '''M''': [buzzing intercom] Miss Moneypenny, give 007 the password we've agreed with Japanese S.I.S.
--> '''[=MoneyPenny=]''': Yes sir.
--> [to Bond]
--> '''[=MoneyPenny=]''': We tried to think of something that you wouldn't forget.
--> '''James Bond''': Yes?
--> '''[=MoneyPenny=]''': "I, love, you". Repeat it please, to make sure you get it.
--> '''James Bond''': Don't worry, I get it.
--> [Later...]
--> '''Tiger Tanaka''': Permit me to introduce myself. I am Tanaka. Please call me Tiger.
--> '''James Bond''': If you're Tanaka, then how do you feel about me?
--> '''Tiger Tanaka''': [the code response] I... love you.
--> '''James Bond''': Well, I'm glad we got that out of the way.
* ''Film/{{Big}}'' has the most complicated example, with a fast sort of song and dance routine.
** Also, when Josh calls his mother, pretending he's a kidnapper, his mother asks him to name the song she used to sing to him when he was younger. Josh tries to dodge the question, but when she insists, he sheepishly sings the song, the title theme of ''The Way We Were''.

to:

** ''Film/XMen1'': After being fooled by [[Characters/XMenFilmSeriesMystique Mystique]] one too many times, Cyclops demands that Wolverine prove he is who he says he is, under threat of being eye-beamed.[[EyeBeams eye-beamed]]. Wolverine's response: "You're a dick." [[SomethingOnlyTheyWouldSay It works.
works.]]
** ''Film/XMenDaysOfFuturePast'': Logan convinces 1973 Charles to hear him out by telling him some details about his childhood that he learned from future Charles and that the younger Xavier hadn't told anyone up until this point in time.
--->'''Logan''':
time:
--->'''Logan:'''
I know your powers came when you were nine. I know you thought you were going crazy when it started, all the voices in your head, and it wasn't until you were twelve that you realized all the voices were in everyone else's head.
* In ''Film/{{Cooperstown}}'', a former baseball player claims to be seeing the ghost of his deceased friend. To figure out if he's lying or not, another character asks him several questions that she thinks Harry won't know, but that the ghost would know. As it turns out, [[spoiler: Harry [[spoiler:Harry was seeing the ghost of his friend. The questions proved it]].
it.]]
* ''Film/StarTrek'' actually gives an example where this doesn't work. Spock Prime greets Kirk with the line, [[Film/StarTrekIITheWrathOfKhan "I have been and always shall be your friend"]]. Except that event happens so far into the future that Kirk and Spock aren't even friends yet in this timeline, so it kind of falls flat. He finally Kirk doesn't get it. Spock resorts to using a [[ExpositionBeam mindmeld]] instead.
* In ''Film/TwelveMonkeys'', Cole can't figure out if he's actually from the future or if he's just crazy. He figures it out when [[spoiler: he [[spoiler:he tells Kathryn to make a phone call for him to a phone he knows will be monitored in the future. Kathryn leaves the message Cole had been told about in the future, which confirms he's from the future]].
* From ''Film/YouOnlyLiveTwice'':
In ''Film/YouOnlyLiveTwice'', Miss Moneypenny abuses her role as creator of Bond's trust password to get him to tell her something she really wanted to hear from him. It doesn't work and just makes everything kind of awkward:
--> '''M''': [buzzing intercom] '''M:''' ''(buzzing intercom)'' Miss Moneypenny, give 007 the password we've agreed with Japanese S.I.S.
--> '''[=MoneyPenny=]''':
S.\\
'''Moneypenny:'''
Yes sir.
--> [to Bond]
--> '''[=MoneyPenny=]''':
sir. ''(to Bond)'' We tried to think of something that you wouldn't forget.
--> '''James Bond''': Yes?
--> '''[=MoneyPenny=]''':
forget.\\
'''Bond:''' Yes?\\
'''Moneypenny:'''
"I, love, you". you." Repeat it please, to make sure you get it.
-->
it.\\
'''James Bond''': Don't worry, I get it.
--> [Later...]
-->
it.\\
''[Later...]''\\
'''Tiger Tanaka''': Tanaka:''' Permit me to introduce myself. I am Tanaka. Please call me Tiger.
--> '''James Bond''':
Tiger.\\
'''Bond:'''
If you're Tanaka, then how do you feel about me?
--> '''Tiger Tanaka''': [the code response]
me?\\
'''Tanaka:'''
I... love you.
--> '''James Bond''':
you.\\
'''Bond''': [[DeadpanSnarker
Well, I'm glad we got that out of the way.
way.]]
* ''Film/{{Big}}'' has the ''Film/{{Big}}'':
** The
most complicated example, prominent trust password is extremely complicated, with a fast sort of song and dance routine.
** Also, when When Josh calls his mother, pretending he's a kidnapper, his mother asks him to name the song she used to sing to him when he was younger. Josh tries to dodge the question, but when she insists, he sheepishly sings the song, the title theme of ''The Way We Were''.



-->'''Mike''': It's me, Mike O'Donnell, your best friend! You have an undescended testicle.
-->'''Ned''': Website/{{Google}}able!
--> '''Mike''': You helped me cheat on a math test, but I got caught.
-->'''Ned''': Public records!
-->'''Mike''': You asked [[Franchise/StarWars Princess Leia]] to Junior Prom!
-->'''Ned''': Covered by the local news!
* In one of the ''Film/TheBourneSeries'' films, it's shown that all Treadstone agents have "Safe" and "Under Duress" passwords.
* ''Film/GroundhogDay'' takes it to extremes. To prove that he really is repeating the day over and over again, Phil walks Rita through a diner, giving the trust passwords for ''everyone in the diner'', none of whom remember telling him those things. She still doesn't quite believe him until he shows he can also predict what people are about to say.
* Parodied in one or more of ''Franchise/ThePinkPanther'' movies. Clouseau asks Dreyfus what his code name is, or what the password is. Dreyfus has to think, then replies in a fury that he doesn't have a codename and there is no password. Clouseau confirms that only the real Dreyfus would know that, causing Dreyfus to become even more angry.
* In ''Film/{{Airheads}}'', to determine whether a record executive actually is an exec, not an undercover cop, Chazz asks him "Whose side did you take in the Music/VanHalen / Roth split: Van Halen or Roth?". When he answers "Van Halen" instead of "Roth", he's concluded to be a cop, but Chazz gives him one more chance, asking "Who would win a wrestling match: [[Music/{{Motorhead}} Lemmy]] or {{God}}?". As he first answers "Lemmy" before answering "God", Rex tells him "Wrong, dickhead! Trick question! Lemmy ''IS'' God!", and he's finally driven away.
* When Sarah encounters Future John Connor in ''Film/TerminatorGenisys'', she suspects him to be a shapeshifted terminator. Connor gains her trust by citing details of the past that only John Connor would know.
* In ''Film/{{Ghost}}'', Patrick Swayze's deceased character is trying to convince his girlfriend that a medium can speak for him. He tries to tell her that he loves her, but this backfires, since he was reluctant to say those words in life. He quickly corrects himself and tells the medium to say "ditto," which is how he would usually respond to his girlfriend telling him that she loves him.
* In ''Film/TheSixthSense'', Lynn Sear [[spoiler: accepts that Cole is telling her the truth -- he really ''can'' see and talk to dead people -- after this exchange]]:
--> '''Cole:''' ''[of his grandmother]'' She wanted me to tell you...
--> '''Lynn:''' Cole, please stop...
--> '''Cole:''' She wanted me to tell you she saw you dance. She said, when you were little, you and her had a fight, right before your dance recital. You thought she didn't come see you dance. She did. She hid in the back so you wouldn't see. She said you were like an angel. She said you came to the place where they buried her. Asked her a question. She said the answer is: "Every day." What did you ask?
--> '''Lynn:''' Do... Do I make her proud?

to:

-->'''Mike''': -->'''Mike:''' It's me, Mike O'Donnell, your best friend! You have an undescended testicle.
-->'''Ned''': Website/{{Google}}able!
-->
testicle.\\
'''Ned''': Website/{{Google}}able!\\
'''Mike''': You helped me cheat on a math test, but I got caught.
-->'''Ned''':
caught.\\
'''Ned''':
Public records!
-->'''Mike''':
records!\\
'''Mike''':
You asked [[Franchise/StarWars Princess Leia]] to Junior Prom!
-->'''Ned''':
Prom!\\
'''Ned''': [[LocalAngle
Covered by the local news!
news!]]
* In one of the ''Film/TheBourneSeries'' ''Film/TheBourneUltimatum'' films, it's shown that all Treadstone agents have "Safe" and "Under Duress" passwords.
passwords. Nicky Parsons is expected to give her "Under Duress" password when Bourne tracks her down; [[spoiler:she doesn't, signaling her defection to Bourne's side.]]
* ''Film/GroundhogDay'' takes it to extremes. To prove that he really is repeating the day over and over again, Phil walks Rita through a diner, giving the trust passwords for ''everyone in the diner'', none of whom remember telling him those things. She still doesn't quite believe him him, until he shows he can also predict what people are about to say.
* Parodied in one or more of several ''Franchise/ThePinkPanther'' movies. Clouseau asks will ask Dreyfus what his code name is, or what the password is. Dreyfus has to think, then replies in a fury that he doesn't have a codename and or that there is no password. Clouseau confirms that only the real Dreyfus would know that, causing but this just angers Dreyfus to become even more angry.
further.
* In ''Film/{{Airheads}}'', to determine whether a record executive actually is an exec, exec and not an undercover cop, Chazz asks him him, "Whose side did you take in the Music/VanHalen / Roth Music/VanHalen[=/=]Roth split: Van Halen or Roth?". When he He incorrectly answers "Van Halen" instead of "Roth", he's concluded to be Halen", outing him as a cop, but cop. Chazz still gives him one more chance, asking "Who would win a wrestling match: [[Music/{{Motorhead}} Lemmy]] or {{God}}?". As he He first answers "Lemmy" before answering "Lemmy", then hastily switches to "God", before Rex tells him him, "Wrong, dickhead! Trick question! Lemmy ''IS'' ''is'' God!", and he's finally driven away.
* When Sarah encounters Future John Connor in In ''Film/TerminatorGenisys'', when Sarah encounters Future John Connor, she suspects him to be a shapeshifted terminator. Connor gains her trust by citing details of the past that only John Connor would know.
* In ''Film/{{Ghost}}'', Patrick Swayze's deceased character is trying to convince his girlfriend that a medium can speak for him. He tries to tell her that he loves her, but this backfires, since he was reluctant to say those words in life. He quickly corrects himself and tells the medium to say "ditto," "ditto", which is how he would usually respond to his girlfriend telling him that she loves him.
* In ''Film/TheSixthSense'', Lynn Sear [[spoiler: accepts [[spoiler:accepts that Cole is telling her the truth -- he really ''can'' see and talk to dead people -- after this exchange]]:
--> '''Cole:''' ''[of his grandmother]'' She [My grandmother] wanted me to tell you...
-->
you...\\
'''Lynn:''' Cole, please stop...
-->
stop...\\
'''Cole:''' She wanted me to tell you she saw you dance. She said, when you were little, you and her had a fight, right before your dance recital. You thought she didn't come see you dance. She did. She hid in the back so you wouldn't see. She said you were like an angel. She said you came to the place where they buried her. Asked her a question. She said the answer is: "Every day." What did you ask?
-->
ask?\\
'''Lynn:''' Do... Do do I make her proud?



* ''The Assignment'' (1997) is about a US naval officer who has an uncanny resemblance to Carlos the Jackal, so he's recruited in a CIA/Mossad scheme to discredit the terrorist. Another terrorist who knows the real Carlos accidentally runs into this {{doppelganger}} at Heathrow Airport. The protagonist tries to bluff his way out by pretending to be Carlos, but when the terrorist responds, "I need to buy a newspaper" realizes too late that it's a password to which he doesn't know the countersign -- his life is only saved by the intervention of a Mossad agent who gets killed in the process. Afterwards his CIA handler mentions a similar incident where he was forced to kill a man who didn't respond with the correct countersign, and later uses this story to [[SpotTheImposter tell the difference between the protagonist and the real Carlos]].
* ''Film/CaptainAmericaCivilWar'': Bucky proves that he's back to his old self [[spoiler:after being re-[[BrainwashedAndCrazy brainwashed]] and causing an international incident]] by remembering that pre-serum Steve used to stuff newspapers in his shoes; he's the only living person other than Steve [[SomethingOnlyTheyWouldSay who would know that]], [[spoiler:and wouldn't remember it if he were still under the effects of the [[MindRape kind of brainwashing]] HYDRA uses]].

to:

* ''The Assignment'' (1997) ''Film/TheAssignment'' is about a US naval officer who has an uncanny resemblance to Carlos the Jackal, so he's recruited in a CIA/Mossad scheme to discredit the terrorist. Another terrorist who knows the real Carlos accidentally runs into this {{doppelganger}} at Heathrow Airport. The protagonist tries to bluff his way out by pretending to be Carlos, but when the terrorist responds, "I need to buy a newspaper" newspaper", the protagonist realizes too late that it's a password to which he doesn't know the countersign -- his life is only saved by the intervention of a Mossad agent who gets killed in the process. Afterwards his CIA handler mentions a similar incident where he was forced to kill a man who didn't respond with the correct countersign, and later uses this story to [[SpotTheImposter tell the difference between the protagonist and the real Carlos]].
* ''Film/CaptainAmericaCivilWar'': Bucky proves that he's back to his old self [[spoiler:after being re-[[BrainwashedAndCrazy brainwashed]] and causing an international incident]] by remembering that pre-serum Steve used to stuff newspapers in his shoes; he's the only living person other than Steve [[SomethingOnlyTheyWouldSay who would know that]], [[spoiler:and he wouldn't remember it if he were still under the effects of the [[MindRape kind of brainwashing]] HYDRA uses]].



* Creator/JorgeLuisBorges' short story ''The Other'' has a clever version of this trope. In it, an older Borges meets his younger self on a bench by a river. The older tells the younger details about their life that no one else could know. Young Borges dismisses this because he could be dreaming. His dream self would of course know all the details of his own life. A few minutes later, Old Borges proves that it is not a dream by reciting a line of French poetry he is sure his younger self has never heard nor could have dreamed up, and showing him a piece of money with a recent date on it. He later realizes that the note he showed his younger self ''[[MindScrew doesn't actually have a date on it]]'' -- [[MindScrew meaning that the younger Borges did in fact dream it, but the older one did not]].
* In ''Literature/ArtemisFowl'', Artemis sets up not one, but two of these in case his memory ever gets wiped by the Fairies. The password for him is a video of himself saying what happened, as Artemis only would believe something he said. Butler's is [[spoiler: Artemis saying his first name: Domovoi]]
* In the last two ''Literature/HarryPotter'' books, the Ministry of Magic suggests people set up a password with their loved ones so as to identify someone disguised with Polyjuice Potion. It's generally treated as a joke in ''Half-Blood Prince'', but becomes deadly serious in ''Deathly Hallows''. (Not only are circumstances more serious, but people have figured out that it's best to make the Q&A spontaneous.)

to:

* Creator/JorgeLuisBorges' short story ''The Other'' has a clever version of this trope. In it, an An older Borges meets his younger self on a bench by a river. The older tells the younger details about their life that no one else could know. Young Borges dismisses this because he could be dreaming. His dream self would of course know all the details of his own life. A few minutes later, as a dream, but Old Borges proves that it is not a dream ThatWasNotADream by reciting a line of French poetry he is sure his younger self has never heard nor could have dreamed up, and showing him a piece of money with a recent date on it. He later realizes that the note he showed his younger self ''[[MindScrew doesn't actually have a date on it]]'' it -- [[MindScrew meaning that the younger Borges did in fact dream it, but the older one did not]].
* In ''Literature/ArtemisFowl'', Artemis sets up not one, but two of these trust passwords for himself and Butler in case his memory ever gets wiped by the Fairies. The Fairies [[MindWipe wipe their memories]]. Artemis' own password for him is a video of himself saying what happened, as Artemis only would only believe something he said. said himself. Butler's is [[spoiler: Artemis saying [[spoiler:Artemis telling him his first name: Domovoi]]
Domovoi]].
* In the last two ''Literature/HarryPotter'' books, the Ministry of Magic suggests people set up a password with their loved ones so as to identify someone disguised with Polyjuice Potion. It's generally treated as a joke in ''Half-Blood Prince'', Prince'' (such as Arthur accidentally outing his secret AffectionateNickname for Molly), but becomes deadly serious in ''Deathly Hallows''. (Not only are Hallows'', as the circumstances are much more serious, but dire, and people have figured out that it's best to make the Q&A spontaneous.)will turn on their loved ones if they don't answer correctly immediately.



* In Marge Piercy's ''He, She & It'', the heroine suspects the VR representation of her husband in traction after a probably fatal incident. She asks him a personal question, and his answer is the lie that she and her real husband put in a government file for just such a test.
* In ''Literature/MaraDaughterOfTheNile'': Sheftu gives Nekonkh a Trust Password for Mara: "Tell her I have not forgotten what I said last night when I took her in my arms." Nekonkh is repulsed by Sheftu's cold-bloodedness, as he is to use the password as part of Mara's [[FeedTheMole loyalty test]].
* Played with in TheHourglassDoor trilogy (As it's full of time travel). In the second book, Leo tells V to go back in time and tell his past self that, "the lady of light" sent him, and that it is time, "to honor his vow," so that Past Leo won't kill Future V. In the third book, main character Abby goes back in time and saves Leo, who calls her his lady of light, and she asks him to promise to do something for the one who asks him to honor the vow. It gets more confusing from there.
* In ''Discworld/TheScienceOfDiscworld II'' after traveling back in time most of the wizards make a point of saying something to their past selves to prove that they are time travelers rather than doubles created by the elves. The exception is Rincewind, who is so jaded by everything that's happened to him in his very eventful life that he just walks up to his past self and says hi.
* In Creator/PatriciaCWrede's ''Literature/TheRavenRing'', Karvonen is captured by the shapeshifting bad guy, and manages to convince him that a) the other characters have a password (they don't) and b) it's in heroine Eleret's native language, which the shapeshifter doesn't speak. This results in "Karvonen" walking up to the others and carefully reciting the phrase "Karvonen says to tell you I'm the shapeshifter."
* In Alistair Maclean's spy novel ''The Dark Crusader'' (published in the USA as ''The Black Shrike'') the hero includes the nonsense word ''Bilex'' in all communications with headquarters to show that the message is genuine and not written under duress. After he is captured, the enemy claim to have sent a fake message that all is well, which presumably would not include the codeword. The twist is that [[spoiler: the hero's boss is actually in league with the enemy, something he realises when his boss takes no action in response to an obviously fake message...which was probably never actually sent anyway]].
* In ''Brotherhood of the Rose'' by David Morrell, the CIA are following Saul until he makes contact with his surrogate brother Chris and they can both be killed. When Saul sets up the meeting, an underling urges spymaster Elliot to let them grab Saul and sweat the meeting place out of him. Elliot turns this idea down, pointing out that Chris and Saul have known each other since they were children and have codes and passwords dating back to then, so they've no way of being sure that Saul couldn't pass on a hidden warning.
* In the non-fiction ''Don't Tell Mum I Work On the Oil Rigs, She Thinks I'm A Piano Player In A Whorehouse'' the author Paul Carter is sent to work in Nigeria. He's given a sentence which the driver picking him up at the airport ''must'' give before he gets in the cab to avoid a NotMyDriver trope ending in robbery and murder. The sentence is somewhat garbled in translation, but close enough.

to:

* In Marge Piercy's ''He, She & It'', ''Literature/HeSheAndIt'', the heroine suspects the VR representation of her husband in traction after a probably fatal incident.incident is not real. She asks him a personal question, and his answer is the lie that she and her real husband put in a government file for just such a test.
* In ''Literature/MaraDaughterOfTheNile'': ''Literature/MaraDaughterOfTheNile'', Sheftu gives Nekonkh a Trust Password for Mara: "Tell her I have not forgotten what I said last night when I took her in my arms." Nekonkh is repulsed by Sheftu's cold-bloodedness, as he is to use the password as part of Mara's [[FeedTheMole loyalty test]].
* Played with in TheHourglassDoor trilogy (As it's full of time travel). ''Literature/TheHourglassDoor'' trilogy: In the second book, Leo tells V to go back in time and tell his past self that, that "the lady of light" sent him, and that it is time, time "to honor his vow," vow" so that Past Leo won't kill Future V. In the third book, main character Abby goes back in time and saves Leo, who calls her his lady "lady of light, light", and she asks him to promise to do something for the one who asks him to honor the vow. It gets more confusing from there.
* In ''Discworld/TheScienceOfDiscworld II'' II'', after traveling back in time time, most of the wizards make a point of saying something to their past selves to prove that they are time travelers rather than doubles created by the elves. The exception is Rincewind, who is so jaded by everything that's happened to him in his very eventful life that he just walks up to his past self and says hi.
"hi".
* In Creator/PatriciaCWrede's ''Literature/TheRavenRing'', Karvonen is captured by the shapeshifting bad guy, and manages to convince him that a) ''(a)'' the other characters have a password (they don't) and b) ''(b)'' it's in heroine Eleret's native language, which the shapeshifter doesn't speak. This results in "Karvonen" walking up to the others and carefully reciting the phrase "Karvonen says to tell you I'm the shapeshifter."
* In Alistair Maclean's spy novel ''The Dark Crusader'' ''Literature/TheDarkCrusader'' (published in the USA as ''The Black Shrike'') Shrike''), the hero includes the nonsense word ''Bilex'' in all communications with headquarters to show that the message is genuine and not written under duress. After he is captured, the enemy claim to have sent a fake message that all is well, which presumably would not include the codeword. The twist is that [[spoiler: the [[spoiler:the hero's boss is actually in league with the enemy, something he realises when his boss takes no action in response to an obviously fake message...message... which was probably never actually sent anyway]].
* In ''Brotherhood of the Rose'' ''Literature/BrotherhoodOfTheRose'' by David Morrell, the CIA are following Saul until he makes contact with his surrogate brother Chris and they can both be killed. When Saul sets up the meeting, an underling urges spymaster Elliot to let them grab Saul and sweat the meeting place out of him. Elliot turns this idea down, pointing out that Chris and Saul have known each other since they were children and have codes and passwords dating back to then, so they've no way of being sure that Saul couldn't pass on a hidden warning.
* In the non-fiction ''Don't Tell Mum I Work On on the Oil Rigs, She Thinks I'm A a Piano Player In A Whorehouse'' in a Whorehouse'', the author Paul Carter is sent to work in Nigeria. He's given a sentence which the driver picking him up at the airport ''must'' give before he gets in the cab to avoid a NotMyDriver trope ending in robbery and murder. The sentence is somewhat garbled in translation, but close enough.enough.
* In Carrie Vaughn's Literature/KittyNorville series, a medium successfully contacts Creator/HarryHoudini, famous in RealLife (as noted in its section below) for leaving codes he would use to try and contact people from beyond the grave, believing that it was all bunk and trying to discredit it. He tells the medium, "Everyone who knew my codes is dead. No one will believe you. But thanks for trying."



** In the two-parter "Human Nature"/"The Family of Blood", Martha Jones, a medical student from the future, uses her knowledge of anatomy to prove that she's not "just" a maid, which she's currently disguised as.

to:

** In the two-parter "Human Nature"/"The Family of Blood", Martha Jones, a medical student from the future, future disguised as a maid, uses her knowledge of anatomy to prove that she's not "just" a maid, which she's currently disguised as.more than she seems.



** And in the season finale, [[spoiler: the metacrisis Doctor whispers something ([[WordOfGod "I love you"]]) to Rose to make her accept him as the Doctor that's right for her, rather than the original]].
** "She told me to warn you. She said two words: [[spoiler: '''[[ArcWords BAD WOLF]]''']]. Well, what does it mean?"
** And from the series six premiere:

to:

** And in "BAD WOLF" were Series One's ArcWords, and they tended to show up even after the season finale, [[spoiler: "arc" was over. More than once, someone could get the metacrisis Doctor's attention as to the severity of the situation (and whether they could be trusted) by saying those words to him.
** In [[Recap/DoctorWhoS30E13JourneysEnd "Journey's End"]], Rose encounters [[DoppelgangerReplacementLoveInterest two Doctors]] and has to decide which one to trust. One tells her [[spoiler:"I love you", which means he's ''not'' the real
Doctor whispers something ([[WordOfGod "I love you"]]) to Rose to make her accept him as -- who infamously CannotSpitItOut -- but she chooses the Doctor doppelganger anyway, because that's right for her, rather than the original]].
** "She told me to warn you. She said two words: [[spoiler: '''[[ArcWords BAD WOLF]]''']]. Well,
what does it mean?"
she's always wanted to hear]].
** And from From the series six premiere:premiere, when Amy needs to get the Doctor to trust her, she tells him a detail only they would know: the Doctor's WackyCravings from their first meeting:



** Played with in season 5. Hurley is afraid of inadvertently being God Tested and revealed to be a time traveller when he's unable to answer a question that someone living in 1977 should be able to. He's right to be afraid of this, given that his example of such a question is "who's President in 1977?" Pierre Chang eventually gets suspicious and trips him up easily.
--->'''Pierre Chang''': What year were you born?\\
'''Hurley''': 1930.\\
'''Pierre Chang''': So you're 47 years old?\\
'''Hurley''': Yes.\\
'''Pierre Chang''': And you fought in the Korean war?\\
'''Hurley''': Ha! No such thing!

to:

** Played with in season 5. Hurley is afraid of inadvertently being God Tested {{God Test}}ed and revealed to be a time traveller traveler when he's unable to answer a question that someone living in 1977 should be able to. He's right to be afraid of this, given that (which in his example of such a question is case goes as far as "who's President in 1977?" 1977?") Pierre Chang eventually gets suspicious and trips him up easily.
--->'''Pierre Chang''': --->'''Pierre:''' What year were you born?\\
'''Hurley''': '''Hurley:''' 1930.\\
'''Pierre Chang''': '''Pierre:''' So you're 47 years old?\\
'''Hurley''': '''Hurley:''' Yes.\\
'''Pierre Chang''': '''Pierre:''' And you fought in the Korean war?\\
'''Hurley''':
UsefulNotes/TheKoreanWar?\\
'''Hurley:'''
Ha! No such thing!



** The team accidentally travels back in time to 1969. Since this was a StableTimeLoop, General Hammond knew to send them with a sealed note explaining things to his rookie past-self. When he finds it, Lieutenant Hammond believes it and helps them escape imprisonment (and remembers to write the note "again" 30 years later.)
** Also in the same incident, O'Neill convinces Lieutenant Hammond the team know him in the future by telling him he watched the first moon landing two weeks ago from his father's bedside after a heart attack.
** In another episode, the team finds a crystal skull inside a chamber filled with radiation and their attempt to examine it results in Daniel being made invisible and immaterial. The rest of the cast has no idea what happened to him until it is revealed that Daniel's grandfather Nick (who had once seen a similar skull and was living in a mental institution) can see him. Jack is skeptical, but is convinced by this exchange:

to:

** The team accidentally travels back in time to 1969. Since this was a StableTimeLoop, General Hammond [[RetroactivePreparation knew to send them with a sealed note note]] explaining things to his rookie past-self. When he finds it, Lieutenant Hammond believes it and helps them escape imprisonment (and remembers to write the note "again" 30 years later.)
** Also in
later). In the same incident, O'Neill convinces Lieutenant Lt. Hammond that the team know knows him in the future by telling him he watched the first moon landing two weeks ago prior from his father's bedside after a heart attack.
** In another episode, the The team finds a crystal skull inside a chamber filled with radiation radiation, and their attempt to examine it results in Daniel being made [[IntangibleMan invisible and immaterial.immaterial]]. The rest of the cast has no idea what happened to him until it is revealed that Daniel's grandfather Nick (who had once seen a similar skull and was living in a mental institution) can see him. Jack is skeptical, but is convinced by this exchange:



'''Daniel''': ''*exasperated*'' Because.\\
'''Jack:''' ''[beat]'' Yeah, okay...

to:

'''Daniel''': ''*exasperated*'' ''(exasperated)'' Because.\\
'''Jack:''' ''[beat]'' ''({{beat}})'' Yeah, okay...



** In ''Film/StargateContinuum'', the trope is subverted twice: O'Neill refuses to believe the alternate timeline SG-1 (partly because what Daniel tries to use--his son's accidental death--didn't happen in the alternate timeline), while Landry cuts them off as they are about to do this by telling them he believes them (having previously seen the tapes of their interrogations).
* In an alternate future of ''Series/StarTrekEnterprise'', the now elderly Captain Jonathan Archer is being cared for by his... caretaker... T'Pol. However, an injury prevents him from remembering all that's happened since he was last on the ''Enterprise''. T'Pol says to him that she fully understands that he might consider all this to be an illusion or an elaborate deception. To alleviate his fears she tells him the story of an old girlfriend he wanted to marry back on Earth. The stunned Archer wants to know just what kind of 'relationship' he and T'Pol have that he'd ever tell her the story. [[ShipTease She'll only say their relationship has "evolved".]]
* In the ''Series/StarTrekTheOriginalSeries'' episode "Whom Gods Destroy", a shapeshifting madman assumes Kirk's appearance and tells Scotty to beam him back aboard. Much to his chagrin, Scotty challenges him with a [[ChessMotif three-dimensional chess move]] "Queen to Queen's level three, sir" -- which only Kirk and Spock knew the appropriate countersign (Queen to King's level one).
* TimeTravel was the whole point of ''Series/SevenDays'', and the team set up a code phrase for the protagonist to use so that they'd always know when he had shown up from the future, and they weren't dealing with a hoax. The password used is Frank contacting Backstep and identifying himself as 'Conundrum'.
** This password is only useful for the first episode, when the team has no idea who he is. After that, he's really just using 'Conundrum' as a codename and to get put through to the right people, because they a) all know Frank, and b) notice when their giant time-traveling sphere vanishes from the hanger.
* In one episode of ''Series/LoisAndClark'', a time-traveller is able to enlist Clark's aid by whispering "I know you're Superman, and I need your help", to him.
* In the ''Series/{{Charmed}}'' episode "That 70's Episode", Prue and Piper convince their past selves to trust them by opening a trick drawer in a cabinet.
** Piper attempts it in another episode, telling their mother they can be trusted because they know she's pregnant with Phoebe. It backfires because, not only does she not know, she believes she's infertile.
* In the ''Series/{{Supernatural}}'' episode "The End", Dean is sent to the future and proves his identity to Future!Dean by telling a story that only he would know:
--> '''Dean''': [[CrowningMomentOfFunny Rhonda Hurley. We were, uh...19. She made us try on her panties. They were pink. And satiny. And you know what? We kind of liked it.]]
** Sam and Dean Winchester have a series of passwords and routines established for if they get separated, captured or arrested. The phrase "Funky Town" means the brother who says it is being held at gun point. "Poughkeepsie" means drop everything and run. A note addressed to "Hilt" and signed "Steve McQueen" means the brother who sent it will create a distraction while the brother who received it makes an escape.
** When Dean travels back in time, he has to convince his mother, Mary, that he is her son sent from the future. He convinces her by telling her that she always sang "Hey Jude" to him as a kid because it was her favorite song.
* In an episode of ''Series/BuckRogersInTheTwentyFifthCentury'', Buck hijacks a Draconian fighter and must prove to another pilot that he's from Earth. The pilot is someone Buck had previously been stranded in the desert with and had shared stories of the past. In this case, Buck proved who he was by giving a description of OJ Simpson. Since Buck had left Earth in 1987, he had no idea that OJ may or may not have turned out to be a double murderer and since the show was filmed prior to this, neither did the writers.
* And in ''Series/BuffyTheVampireSlayer'', this classic exchange. Makes even more sense when you realize the above ''Film/XMen1'' "You're a dick" line was also penned by Creator/JossWhedon.
--> '''Giles:''' Cordelia, it's me! It's me!
--> '''Cordelia:''' How do we know it's really you and not zombie Giles?
--> '''Giles:''' Cordelia, do stop being tiresome.
--> '''Cordelia:''' It's him.
** In another episode, Xander does the [[{{ComicStrip/Peanuts}} Snoopy Dance]] to prove he's Xander for Willow.
*** He also tells a story about one of his early birthdays where he didn't get a firetruck and was sad, but then the neighbours house caught fire so real trucks came and he always thought Willow might have set the fire "and if you did you can tell me". Played with in that he's doing all this to prove that he's not his EvilTwin who the rest of the Scoobies have gone off to fight. A) His twin would know all this stuff anyway, given that Xander had been duplicated and B) Willow wasn't even aware there ''was'' a twin so she had no reason to doubt he was Xander. She just let him talk because he didn't give her the option not to.
* In one episode of ''{{Series/Bones}}'', a boy is kidnapped. Booth asks the dad what password he can use so the boy will trust him during the rescue. (It's Paladin, and the rescue scene is [[CrowningMomentOfAwesome awesome]] and [[CrowningMomentofHeartwarming heartwarming]].)
** And the appropriateness of this trust password for Agent Booth, a Roman Catholic FBI agent, is lampshaded by his boss:
-->"Paladin." Defender of the Faith.
* An episode of ''Series/StarTrekTheNextGeneration'' had Worf visited by a Klingon who first claims to be an advisor, and then later admits that he is Worf's now-grown son Alexander, traveling back in time to urge his younger self into becoming a warrior. To prove his identity, Worf asks future!Alexander to say what his mother said before she died.

to:

** In ''Film/StargateContinuum'', the trope is subverted twice: O'Neill refuses to believe the alternate timeline SG-1 (partly because what Daniel tries to use--his use -- his son's accidental death--didn't death -- didn't happen in the alternate timeline), while Landry cuts them off as they are about to do this by telling them he believes them (having previously seen the tapes of their interrogations).
* In an alternate future of ''Series/StarTrekEnterprise'', the now elderly Captain Jonathan Archer is being cared for by his... caretaker... T'Pol. However, an injury prevents him from remembering all that's happened since he was last on the ''Enterprise''. T'Pol says to him that she fully understands that he might consider all this to be an illusion or an elaborate deception. To alleviate his fears she tells him the story of an old girlfriend he wanted to marry back on Earth. The stunned Archer wants to know just what kind of 'relationship' he and T'Pol have that he'd ever tell her the story. [[ShipTease She'll only say their relationship has "evolved".]]
*
''Franchise/StarTrek'':
**
In the ''Series/StarTrekTheOriginalSeries'' episode "Whom Gods Destroy", a shapeshifting madman assumes Kirk's appearance and tells Scotty to beam him back aboard. Much to his chagrin, Scotty challenges him with a [[ChessMotif three-dimensional chess move]] "Queen to Queen's level three, sir" -- to which only Kirk and Spock knew the appropriate countersign (Queen to King's level one).
* TimeTravel was the whole point of ''Series/SevenDays'', and the team set up a code phrase for the protagonist to use so that they'd always know when he had shown up from the future, and they weren't dealing with a hoax. The password used is Frank contacting Backstep and identifying himself as 'Conundrum'.
** This password is only useful for the first episode, when the team has no idea who he is. After that, he's really just using 'Conundrum' as a codename and to get put through to the right people, because they a) all know Frank, and b) notice when their giant time-traveling sphere vanishes from the hanger.
* In one episode of ''Series/LoisAndClark'', a time-traveller is able to enlist Clark's aid by whispering "I know you're Superman, and I need your help", to him.
* In the ''Series/{{Charmed}}'' episode "That 70's Episode", Prue and Piper convince their past selves to trust them by opening a trick drawer in a cabinet.
** Piper attempts it in another episode, telling their mother they can be trusted because they know she's pregnant with Phoebe. It backfires because, not only does she not know, she believes she's infertile.
* In the ''Series/{{Supernatural}}'' episode "The End", Dean is sent to the future and proves his identity to Future!Dean by telling a story that only he would know:
--> '''Dean''': [[CrowningMomentOfFunny Rhonda Hurley. We were, uh...19. She made us try on her panties. They were pink. And satiny. And you know what? We kind of liked it.]]
** Sam and Dean Winchester have a series of passwords and routines established for if they get separated, captured or arrested. The phrase "Funky Town" means the brother who says it is being held at gun point. "Poughkeepsie" means drop everything and run. A note addressed to "Hilt" and signed "Steve McQueen" means the brother who sent it will create a distraction while the brother who received it makes an escape.
** When Dean travels back in time, he has to convince his mother, Mary, that he is her son sent from the future. He convinces her by telling her that she always sang "Hey Jude" to him as a kid because it was her favorite song.
* In an episode of ''Series/BuckRogersInTheTwentyFifthCentury'', Buck hijacks a Draconian fighter and must prove to another pilot that he's from Earth. The pilot is someone Buck had previously been stranded in the desert with and had shared stories of the past. In this case, Buck proved who he was by giving a description of OJ Simpson. Since Buck had left Earth in 1987, he had no idea that OJ may or may not have turned out to be a double murderer and since the show was filmed prior to this, neither did the writers.
* And in ''Series/BuffyTheVampireSlayer'', this classic exchange. Makes even more sense when you realize the above ''Film/XMen1'' "You're a dick" line was also penned by Creator/JossWhedon.
--> '''Giles:''' Cordelia, it's me! It's me!
--> '''Cordelia:''' How do we know it's really you and not zombie Giles?
--> '''Giles:''' Cordelia, do stop being tiresome.
--> '''Cordelia:''' It's him.
** In another episode, Xander does the [[{{ComicStrip/Peanuts}} Snoopy Dance]] to prove he's Xander for Willow.
*** He also tells a story about one of his early birthdays where he didn't get a firetruck and was sad, but then the neighbours house caught fire so real trucks came and he always thought Willow might have set the fire "and if you did you can tell me". Played with in that he's doing all this to prove that he's not his EvilTwin who the rest of the Scoobies have gone off to fight. A) His twin would know all this stuff anyway, given that Xander had been duplicated and B) Willow wasn't even aware there ''was'' a twin so she had no reason to doubt he was Xander. She just let him talk because he didn't give her the option not to.
* In one episode of ''{{Series/Bones}}'', a boy is kidnapped. Booth asks the dad what password he can use so the boy will trust him during the rescue. (It's Paladin, and the rescue scene is [[CrowningMomentOfAwesome awesome]] and [[CrowningMomentofHeartwarming heartwarming]].)
** And the appropriateness of this trust password for Agent Booth, a Roman Catholic FBI agent, is lampshaded by his boss:
-->"Paladin." Defender of the Faith.
*
An episode of ''Series/StarTrekTheNextGeneration'' had Worf visited by a Klingon who first claims to be an advisor, and then later admits that he is Worf's now-grown son Alexander, traveling back in time to urge his younger self into becoming a warrior. To prove his identity, Worf asks future!Alexander to say what his mother said before she died.



* In ''Series/TheWestWing'', the word "Sagittarius" is used to denote that person knows about Jed Bartlet's MS.
* In the series 2 premiere of ''{{Series/Misfits}}'', the gang have to deal with a shapeshifter. In order to make sure it's really them, they greet each other with "Monkeyslut!" As befits their general methods, this is horribly ineffective. When one of them does encounter the shifter he just says it with prompting, and fails to notice the shifter's look of confusion.
* An unintentional variation occurs in ''Series/{{Farscape}}''. John is having a normal conversation with Aeryn until he mentions [[spoiler:her baby]] and she doesn't know what he's talking about. This gives away that she is a [[spoiler: bioloid duplicate and the real Aeryn has been kidnapped]].

to:

** In an alternate future of ''Series/StarTrekEnterprise'', the now elderly Captain Jonathan Archer is being cared for by his "caretaker" T'Pol. However, an injury prevents him from remembering all that's happened since he was last on the ''Enterprise''. T'Pol says to him that she fully understands that he might consider all this to be an illusion or an elaborate deception. To alleviate his fears, she tells him the story of an old girlfriend he wanted to marry back on Earth. The stunned Archer wants to know just what kind of "relationship" he and T'Pol have that he'd ever tell her the story. [[ShipTease She'll only say their relationship has "evolved".]]
* TimeTravel was the whole point of ''Series/SevenDays'', and the team set up a code phrase for the protagonist to use so that they'd always know when he had shown up from the future, and they weren't dealing with a hoax. The password used is Frank contacting Backstep and identifying himself as "Conundrum". Interestingly, it was never used this way after the first episode, once the team knows full well who he is -- it's just a signal for them to put him through to the right people.
* In one episode of ''Series/LoisAndClark'', a time-traveller is able to enlist Clark's aid by whispering to him, "I know you're Superman, and I need your help."
* ''Series/{{Charmed}}'':
** In "That 70's Episode", Prue and Piper convince their past selves to trust them by opening a trick drawer in a cabinet.
** Piper attempts it in another episode, telling their mother they can be trusted because they know she's pregnant with Phoebe. It backfires because not only does she not know, she believes she's infertile.
* ''Series/{{Supernatural}}'':
** Sam and Dean have a series of passwords and routines established for if they get separated, captured or arrested. The phrase "Funky Town" means the brother who says it is being held at gunpoint. "Poughkeepsie" means drop everything and run. A note addressed to "Hilt" and signed "Steve McQueen" means the brother who sent it will create a distraction while the brother who received it makes an escape.
** In "The End", Dean is sent to the future and proves his identity to Future!Dean by telling a story that only he would know:
--> '''Dean:''' Rhonda Hurley. We were, uh... 19. She made us try on her panties. [[CrowningMomentOfFunny They were pink. And satiny. And you know what? We kind of liked it.]]
** When Dean travels back in time, he has to convince his mother, Mary, that he is her son sent from the future. He convinces her by telling her that she always sang "[[Music/TheBeatles Hey Jude]]" to him as a kid because it was her favorite song.
* In an episode of ''Series/BuckRogersInTheTwentyFifthCentury'', Buck hijacks a Draconian fighter and must prove to another pilot that he's from Earth. The pilot is someone Buck had previously been stranded in the desert with and had shared stories of the past. In this case, Buck proved who he was by giving a description of OJ Simpson. Since Buck had left Earth in 1987, he had no idea that OJ may or may not have turned out to be a double murderer and since the show was filmed prior to this, neither did the writers.
* ''Series/BuffyTheVampireSlayer'' was never known to use this trope straight, which makes sense, as it was written by Creator/JossWhedon (who also gave us [[Film/XMen1 Wolverine's "You're a dick" line]]):
** Giles tries to prove his identity:
-->'''Giles:''' Cordelia, it's me! It's me!\\
'''Cordelia:''' How do we know it's really you and not zombie Giles?\\
'''Giles:''' Cordelia, do stop being tiresome.\\
'''Cordelia:''' It's him.
** Xander does the [[{{ComicStrip/Peanuts}} Snoopy Dance]] to prove he's Xander for Willow.
** Xander tells a story about one of his early birthdays to prove his identity. He wanted a fire truck but didn't get one, which made him sad, but then the neighbor's house caught fire for real, and he got to see real fire trucks. He adds that he always thought Willow might have set the fire ("if you did you can tell me"). The problem with this is ''(a)'' he's trying to prove he's not his EvilTwin, who would know this anyway, and ''(b)'' Willow wasn't aware that there ''was'' a twin and thus had no reason to doubt he was Xander.
* In one episode of ''{{Series/Bones}}'', a boy is kidnapped. Booth asks the dad what password he can use so the boy will trust him during the rescue. (It turns out to be "Paladin" -- ''i.e.'' "defender of the faith", which as his boss notes is an oddly appropriate one for a Catholic FBI agent.)
* In ''Series/TheWestWing'', the word "Sagittarius" is used to denote that a person who knows about Jed Bartlet's MS.
multiple sclerosis.
* In the series 2 premiere of ''{{Series/Misfits}}'', the gang have to deal with a shapeshifter. In order to make sure it's really them, they greet each other with "Monkeyslut!" As befits their general methods, this is horribly ineffective. When one of them does encounter the shifter shifter, he just says it with prompting, and fails to notice the shifter's look of confusion.
* An unintentional variation occurs in ''Series/{{Farscape}}''. John is having a normal conversation with Aeryn until he mentions [[spoiler:her baby]] and she doesn't know what he's talking about. This gives away that she is a [[spoiler: bioloid [[spoiler:bioloid duplicate and the real Aeryn has been kidnapped]].



** In the episode "Transference", Clark Kent and Lionel Luthor [[FreakyFridayFlip swap bodies]]. In Lionel's body, Clark convinces Ma Kent it's really him by telling the story of how he discovered SuperSpeed at age 6.
** Subverted in "Apocalypse". Clark tries to prove he's a friend to Chloe by revealing some of their past experiences, but since he's in an alternate universe where they have never met, it fails.
* In one episode of ''Series/WithoutATrace'', the episode's missing person is a preteen girl who's been kidnapped as part of a pedophile ring. At the episode's outset, while talking about her quirks, the girl's uncle tells Malone that his nickname for the child is "Chicken Little." Much later, this comes in handy when Malone, having determined where the girl's abductor is, poses as a pedophile customer and gets to talk to the girl, but he can't say anything too suspicious to her since they're both still in the antagonist's line of sight. What does he wind up saying to gain her trust?

to:

** In the episode "Transference", Clark Kent and Lionel Luthor [[FreakyFridayFlip swap bodies]]. In Lionel's body, Clark convinces Ma Kent it's really him by telling the story of how he discovered SuperSpeed at age 6.
** Subverted in "Apocalypse". "Apocalypse": Clark tries to prove he's a friend to Chloe by revealing some of their past experiences, but since he's in an alternate universe AlternateUniverse where they have never met, it fails.
* In one episode of ''Series/WithoutATrace'', the episode's missing person is a preteen girl who's been kidnapped as part of a pedophile ring. At the episode's outset, while talking about her quirks, the girl's uncle tells Malone that his nickname for the child is "Chicken Little." Little". Much later, this comes in handy when Malone, having determined where the girl's abductor is, poses as a pedophile customer and gets to talk to the girl, but he can't say anything too suspicious to her since they're both still in the antagonist's line of sight. What does he wind up saying to gain her trust?



-->'''Donkeylips:''' What are the four S's of warfare?
-->'''Pinsky:''' Strength, strategy, and surprise.
-->'''Z.Z.:''' It's Pinsky!
-->'''Donkeylips:''' Shhhh!
-->'''Pinsky:''' That's the fourth S.
* Ichabod and Abbie from ''Series/SleepyHollow'' use a fist-bump to identify each other in Purgatory, as Abbie had recently taught it to Ichabod. Also while in Purgatory, Abbie correctly identifies a Crane imposter since the fake didn't pronounce her title using Crane's insistent British pronunciation: "Lef-tenant".
* In ''Series/JessicaJones2015'', Trish and Jessica decide they need some sort of signal to indicate Jess is not under Kilgrave's mind control. Since Kilgrave would make Jessica pretend like everything's normal, they decide to use a phrase that Jessica would never say: [[spoiler:"I love you."]]

to:

-->'''Donkeylips:''' What are the four S's of warfare?
-->'''Pinsky:'''
warfare?\\
'''Pinsky:'''
Strength, strategy, and surprise.
-->'''Z.
surprise.\\
'''Z.
Z.:''' It's Pinsky!
-->'''Donkeylips:''' Shhhh!
-->'''Pinsky:'''
Pinsky!\\
'''Donkeylips:''' Shhhh!\\
'''Pinsky:'''
That's the fourth S.
* In ''Series/SleepyHollow'', Ichabod and Abbie from ''Series/SleepyHollow'' use a fist-bump to identify each other in Purgatory, as Abbie had recently taught it to Ichabod. Also while in Purgatory, Abbie correctly identifies a Crane imposter since the fake didn't pronounce her title using Crane's insistent British pronunciation: "Lef-tenant".
* In ''Series/JessicaJones2015'', Trish and Jessica decide they need some sort of signal to indicate Jess is not under Kilgrave's mind control. Since Kilgrave would make Jessica pretend like everything's normal, they decide to use a phrase that Jessica [[SomethingTheyWouldNeverSay would never say: say:]] [[spoiler:"I love you."]]



* ''Series/QuantumLeap'': Sam has leaped into an illiterate murderer on the run who is holding a woman and her daughter hostage. He decides to drop the {{masquerade}}, telling her he's a doctor from the future in a TimeTravel experiment. She doesn't believe him. Then he notices her medical textbook, and she reveals that she's in medical school. So he has her quiz him on medical stuff to prove that he's telling the truth. At first she still doesn't believe him ,saying that he looked at the book already, so could have memorized the information. Sam quickly fires back: "When was the last time you met an illiterate speed-reader?"

to:

* ''Series/QuantumLeap'': Sam has leaped into an illiterate murderer on the run who is holding a woman and her daughter hostage. He decides to drop the {{masquerade}}, telling her he's a doctor from the future in a TimeTravel experiment. She doesn't believe him. Then he notices her medical textbook, and she reveals that she's in medical school. So he has her quiz him on medical stuff to prove that he's telling the truth. At first she still doesn't believe him ,saying him, saying that he looked at the book already, so could have memorized the information. Sam quickly fires back: "When was the last time you met an illiterate speed-reader?"



* In Brad Paisley's "Letter to Me", he says that if he could send a letter back to himself when he was still in high school, he'd prove to his past self it was really him by telling him to look under the bed for the Skoal (chewing tobacco) can and Playboy no one else knew he had.

to:

* In Brad Paisley's Music/BradPaisley's "Letter to Me", he says that if he could send a letter back to himself when he was still in high school, he'd prove to his past self it was really him by telling him to look under the bed for the Skoal (chewing tobacco) can and Playboy no one else knew he had.



* [[TimeMaster Span]][[TimeTravel ners]] in ''TabletopGame/{{Continuum}}'' use a form of sign/countersign to identify other spanners. They ask what time it is. [[{{Muggles}} Levellers]] will respond with the time. Other spanners will respond by repeating the question back to the asker, word for word.

to:

* In ''TabletopGame/{{Continuum}}'', [[TimeMaster Span]][[TimeTravel ners]] in ''TabletopGame/{{Continuum}}'' Spanners]] use a form of sign/countersign to identify other spanners. They ask what time it is. [[{{Muggles}} Levellers]] will respond with the time. Other spanners will respond by repeating the question back to the asker, word for word.



* In ''[[VideoGame/ModernWarfare Call of Duty: Modern Warfare 2]]'', the trust password for identifying ally under EMP is "Star", which the proper response is "Texas", as seen in Second Sun stage.
* In ''VideoGame/EscapeFromMonkeyIsland'', Guybrush asks his future counterpart to guess what number he's thinking of. Since you 'remember' what future-Guybrush said to past-Guybrush, you can answer him.
* In ''VideoGame/PrinceOfPersiaTheSandsOfTime'', the Prince proves his story to the princess (events that never happened due to the events in the game) by telling her a word invented by her mother, Kakolukia.

to:

* In ''[[VideoGame/ModernWarfare Call of Duty: Modern Warfare 2]]'', the trust password for identifying ally under EMP is "Star", to which the proper response is "Texas", as seen in Second Sun stage.
* In ''VideoGame/EscapeFromMonkeyIsland'', Guybrush asks his future counterpart to guess what number he's thinking of. Since you 'remember' "remember" what future-Guybrush said to past-Guybrush, you can answer him.
* In ''VideoGame/PrinceOfPersiaTheSandsOfTime'', the Prince proves his story to the princess (events that never happened due to the events in the game) by telling her a word invented by her mother, Kakolukia."Kakolukia".



* A non-verbal example in ''VideoGame/{{Geist}}''. Since Raimi has the ability to BodySurf, he has to prove his identity to Bryson by reproducing their SecretHandshake.

to:

* A non-verbal example in ''VideoGame/{{Geist}}''. ''VideoGame/{{Geist}}'': Since Raimi has the ability to BodySurf, he has to prove his identity to Bryson by reproducing their SecretHandshake.



* Early on in ''VideoGame/FinalFantasyVIII'' the PlayerParty is sent on a mission to aide [[LaResistance an anti government group called "The Forest Owls"]] and are given a Password to confirm their identity. Upon reaching the rendezvous point and saying the password to the group's representative ([[ButThouMust regardless of whether or not you gave the correct response]]), he takes you to meet the other members.
* In the ''VideoGame/{{Portal 2}}'' Perpetual Testing Initiative DLC, Cave Johnson realizes that it's very difficult to discern who is the original Cave, and who's from an Alternate Universe. He therefore announces that his trust password is "chariots", and only messages where he says that word come from the real him. Of course, he then discovers that there's an alternate him who just likes to say "chariots" randomly, so he changes the password to him saying it twice in a row; "chariots, chariots". You will never hear so many references to ancient Greek vehicles.
* In ''VideoGame/FullThrottle'', at one point Ben is [[spoiler: about to be (painfully) killed by a gang led by Maureen, who believes that Ben killed her father Malcolm. Of course, Ben's innocent, and to prove it, you have to call Maureen by her childhood nickname, "Diapered Dynamo," which Malcolm told you shortly before he died]].
* ''VideoGame/FireEmblemAwakening'' has several [[spoiler: for most child characters. Generally they prove their identity with a future version of a unique item, generally a wedding ring but in one case Falchion. Amusingly, one character points out the problem with the item passwords; it is possible that the person presenting it murdered the time-traveller and stole their mom's wedding ring]].

to:

* Early on in ''VideoGame/FinalFantasyVIII'' the PlayerParty is sent on a mission to aide aid [[LaResistance an anti government group called "The Forest Owls"]] and are is given a Password to confirm their identity. Upon reaching the rendezvous point and saying the password to the group's representative ([[ButThouMust regardless of whether or not you gave the correct response]]), he takes you to meet the other members.
* In the ''VideoGame/{{Portal 2}}'' Perpetual Testing Initiative DLC, Cave Johnson realizes that it's very difficult to discern who is the original Cave, and who's from an Alternate Universe.AlternateUniverse. He therefore announces that his trust password is "chariots", and only messages where he says that word come from the real him. Of course, he then discovers that there's an alternate him who just likes to say "chariots" randomly, so he changes the password to him saying it twice in a row; row: "chariots, chariots". You will never hear so many references to ancient Greek vehicles.
* In ''VideoGame/FullThrottle'', at one point Ben is [[spoiler: about [[spoiler:about to be (painfully) painfully killed by a gang led by Maureen, who believes that Ben killed her father Malcolm. Of course, Ben's innocent, and to prove it, you have to call Maureen by her childhood nickname, "Diapered Dynamo," Dynamo", which Malcolm told you shortly before he died]].
* ''VideoGame/FireEmblemAwakening'' has several [[spoiler: for [[spoiler:for most child characters. Generally they prove their identity with a future version of a unique item, generally a wedding ring but in one case Falchion. Amusingly, one character points out the problem with the item passwords; it is possible that the person presenting it murdered the time-traveller and stole their mom's wedding ring]].



** In the ''Citadel DLC'' for the third game, Shepard can prove to Traynor that [[spoiler: it was their evil clone that just fired her and threw her off the ''Normandy'']], by describing the toothbrush that Traynor mentioned as wanting to buy during their [[ChekhovsGag first conversation]]. Alternatively, a Female Shepard in a romance with her can do this via a ShutUpKiss.

to:

** In the ''Citadel DLC'' for the third game, Shepard can prove to Traynor that [[spoiler: it [[spoiler:it was their evil clone that just fired her and threw her off the ''Normandy'']], by describing the toothbrush that Traynor mentioned as wanting to buy during their [[ChekhovsGag first conversation]]. Alternatively, a Female Shepard in a romance with her can do this via a ShutUpKiss.



* In ''VideoGame/{{Undertale}}'', if the player loads the game immediately after receiving a pacifist judgement from [[Characters/UndertaleSans Sans]] and receive it again, he will notice that you seem to have heard his speech before, so to put you to the test he gives you a TrustPassword that he's been setting up [[CrazyPrepared just in case he ever needed to verify if someone's a time traveler]]. If you load again, the playable character will tell Sans the password, "I'm a stupid doodoo butt," and he will, in turn, give you the ''true'' trust password that will verify, once and for all, that you're a time traveler. Load again and the playable character will give Sans the second password, "I'm the legendary fartmaster," and he will, in turn, give you the key to his room.
* In ''VideoGame/{{Dragonsphere}}'' a group of guards bar you (even though you are their king) from entering a land of shapeshifters for concern that the "you" who ends up returning may in fact be a shapeshifter who took your place. This is resolved by giving them an item from your inventory (any item will do) so that they will know that the real "you" will ask for that item upon your return. [[spoiler: Ironically, you actually ''are'' [[TomatoInTheMirror a shapeshifter all along, you just don't realise it at first.]]]]

to:

* In ''VideoGame/{{Undertale}}'', if the player loads the game immediately after receiving a pacifist judgement from [[Characters/UndertaleSans Sans]] and receive receives it again, he will notice that you seem to have heard his speech before, so before; to put you to the test test, he gives you a TrustPassword Trust Password that he's been setting up [[CrazyPrepared just in case he ever needed to verify if someone's a time traveler]]. If you load again, the playable character will tell Sans the password, "I'm a [[BigStupidDoodooHead stupid doodoo butt," butt]]," and he will, in turn, give you the ''true'' trust password that will verify, once and for all, that you're a time traveler. Load again and the playable character will give Sans the second password, "I'm the legendary fartmaster," and he will, in turn, give you the key to his room.
* In ''VideoGame/{{Dragonsphere}}'' a group of guards bar you (even though you are their king) from entering a land of shapeshifters for shapeshifters, even though you are their king, out of concern that the "you" who ends up returning may in fact be a shapeshifter who took your place. This is resolved by giving them an item from your inventory (any item will do) so that they will know that the real "you" will ask for that item upon your return. [[spoiler: Ironically, you actually ''are'' [[TomatoInTheMirror a shapeshifter all along, you just don't realise it at first.]]]]



* ''Webcomic/BobAndGeorge'' hangs a lampshade on Bill and Ted when time travel becomes a regular occurrence in the comic; of course, since Mega Man and Bass are [[IdiotHero legendarily stupid]], HilarityEnsues.

to:

* ''Webcomic/BobAndGeorge'' hangs a lampshade on Bill and Ted pay homage to ''Film/BillAndTedsExcellentAdventure'' this way when time travel TimeTravel becomes a regular occurrence in the comic; of course, since Mega Man and Bass are [[IdiotHero legendarily stupid]], HilarityEnsues.it goes about the same way.



* During their adventures in the Punyverse in ''Webcomic/SluggyFreelance'', Bun-Bun cons Lord Grater into believing he works for his boss, Zorgon Gola. Lord Grater responds "if you know everything about me, what am I thinking about right now?" Bun-bun responds that the infomation is [[http://www.sluggy.com/comics/archives/daily/010704 classified,]] which instantly appeases him.
** [[spoiler: {{Inverted|Trope}}]] another time in "Oceans Unmoving". (Big spoiler alert.) [[spoiler: Bun-bun can't appear himself to his past self as himself, because he knows that if he were to see someone claiming to be himself from the future, he'd figure it was a trap and kill them, expecting that if it were really him he would have expected that.]]
* ''Webcomic/{{Panthera}}'' uses this. When Onca tries to tell Tigris that [[spoiler: Ovid isn't the evil corporation they've been told it is, Tigris thinks Onca betrayed Panthera and attacks her]]. However, when Pardus shows up, she tells him that Leo told her [[spoiler: [[http://www.pantheracomic.com/?p=1241 Pardus dyes his fur]]]]. Pardus knows Leo wouldn't tell her unless he ''had to'' to validate a message to the others.
* Double-subverted in ''Webcomic/TheInexplicableAdventuresOfBob''. In the dragon Hibachi's first appearance, he claims to be a friend of Mrs. Primrose who'd been sent to pick up the box she had left with Bob. Bob is understandably suspicious, and demands the seemingly-useless Trust Password of her favorite color. Turns out it's such an obscure color (a specific discontinued shade of paint), and has such an involved story attached to it that it really ''would'' be impossible for anyone who didn't know her to guess.
* In ''{{Webcomic/Homestuck}}'', Jade implements a system of these, though it's less about trust and more about trying to keep her conversations relatively linear since the Trolls tend to skip around a lot regarding time shenanigans.
* Used in ''{{Webcomic/Skullkickers}}''. When Shorty and Baldy make a stop in a tavern while hunting a doppelganger, Baldy suggests establishing a trust password, so that they will know if the doppelganger is impersonating the other. Shorty suggests some passwords, but Baldy dismisses all the Shorty's suggestions... [[spoiler:and kills the false "Shorty" on the spot. As it happens, they'd already established such a password.]]

to:

* ''Webcomic/SluggyFreelance'':
**
During their adventures in the Punyverse in ''Webcomic/SluggyFreelance'', Punyverse, Bun-Bun cons Lord Grater into believing he works for his boss, Zorgon Gola. Lord Grater responds responds, "if you know everything about me, what am I thinking about right now?" Bun-bun Bun-Bun responds that the infomation is [[http://www.sluggy.com/comics/archives/daily/010704 classified,]] which instantly appeases him.
** [[spoiler: {{Inverted|Trope}}]] another time in In "Oceans Unmoving". (Big spoiler alert.) [[spoiler: Bun-bun Unmoving", (major spoilers), [[spoiler:it's {{inverted|trope}}. Bun-Bun can't appear himself to his past self as himself, because he knows that if he were to see someone claiming to be himself from the future, he'd figure it was a trap and kill them, expecting that if it were really him he would have expected that.]]
* ''Webcomic/{{Panthera}}'' uses this. When In ''Webcomic/{{Panthera}}'', when Onca tries to tell Tigris that [[spoiler: Ovid isn't the evil corporation they've been told it is, Tigris thinks Onca betrayed Panthera and attacks her]]. However, when Pardus shows up, she tells him that Leo told her [[spoiler: [[http://www.[[spoiler:[[http://www.pantheracomic.com/?p=1241 Pardus dyes his fur]]]]. Pardus knows Leo wouldn't tell her that unless he ''had to'' to validate a message to the others.
* Double-subverted in ''Webcomic/TheInexplicableAdventuresOfBob''. In the dragon Hibachi's first appearance, he claims to be a friend of Mrs. Primrose who'd been sent to pick up the box she had left with Bob. Bob is understandably suspicious, and demands the seemingly-useless Trust Password of her favorite color. Turns out it's such an obscure color (a specific discontinued shade of paint), and it has such an involved story attached to it that it, it really ''would'' be impossible for anyone who didn't know her to guess.
* In ''{{Webcomic/Homestuck}}'', Jade implements a system of these, though it's less about trust and more about trying to keep her conversations relatively linear linear, since the Trolls tend to skip around a lot regarding time shenanigans.
* Used in ''{{Webcomic/Skullkickers}}''. When In ''{{Webcomic/Skullkickers}}'', when Shorty and Baldy make a stop in a tavern while hunting a doppelganger, Baldy suggests establishing a trust password, so that they will know if the doppelganger is impersonating the other. Shorty suggests some passwords, but Baldy dismisses all the of Shorty's suggestions... suggestions [[spoiler:and kills the false "Shorty" on the spot. As it happens, they'd already established such a password.]]



* In ''[[Machinima/RedVsBlue Red vs.Blue: Reconstruction]]'' Agent Washington verifies that he is from Command to the Reds by knowing Sarges ultimate secret Password. [[spoiler: It's "[[ThePasswordIsAlwaysSwordfish password]]".]]

to:

* In ''[[Machinima/RedVsBlue Red vs.Blue: Reconstruction]]'' Agent Washington verifies to the Reds that he is from Command to the Reds by knowing Sarges Sarge's ultimate secret Password. password: [[spoiler: It's it's "[[ThePasswordIsAlwaysSwordfish password]]".]]



* ''WebSerial/{{Worm}}'' has passwords as standard when fighting Strangers[[note]]people whose powers can mess with perceptions[[/note]] and Masters[[note]]people who can control others[[/note]]. [[spoiler: The most prominent example of this is after the [[VillainProtagonist protagonists]] capture and [[PeoplePuppets bodyjack]] Shadow Stalker in order to infiltrate the Wards. When Weld uses the standard password, they're able to make Shadow Stalker reply with the standard countersign indicating that she's uncompromised... but are at a loss when Weld asks who it was Shadow Stalker recently got in trouble for harassing. The incorrect response turns an until-then-successful infiltration into a firefight.]]
* In a "Sparks Nevada, Marshal on Mars" episode of the ''Podcast/ThrillingAdventureHour'', the first time Croach the Tracker sees Sparks Nevada after [[spoiler:returning from the dead]], Nevada needs more than just Croach's word that it's really him and demands something only the two of them would know about. To Nevada's dismay, Croach chooses to use the time Nevada massaged his egg sacks in the second episode.

to:

* ''WebSerial/{{Worm}}'' has passwords as standard when fighting Strangers[[note]]people whose powers Strangers (who can mess with perceptions[[/note]] perceptions) and Masters[[note]]people who Masters (who can control others[[/note]]. [[spoiler: fight with others). The most prominent example of this is after [[spoiler:after the [[VillainProtagonist protagonists]] capture and [[PeoplePuppets bodyjack]] Shadow Stalker in order to infiltrate the Wards. When Weld uses the standard password, they're able to make Shadow Stalker reply with the standard countersign indicating that she's uncompromised... uncompromised -- but they are at a loss when Weld asks who it was Shadow Stalker recently got in trouble for harassing. The incorrect response turns an until-then-successful infiltration into a firefight.]]
* In a the "Sparks Nevada, Marshal on Mars" episode of the ''Podcast/ThrillingAdventureHour'', the first time Croach the Tracker sees Sparks Nevada after [[spoiler:returning from the dead]], Nevada needs more than just Croach's word that it's really him and demands something only the two of them would know about. To Nevada's dismay, Croach chooses to use the time Nevada massaged his egg sacks in the second episode.



* In the ''WesternAnimation/JusticeLeague'' episode where Flash and Lex Luthor switch minds, Flash proves he's really himself again by starting to reveal Green Lantern's old nickname.

to:

* In the ''WesternAnimation/JusticeLeague'' episode where ''WesternAnimation/JusticeLeague'', when Flash and Lex Luthor switch minds, Flash proves he's really himself again by starting to reveal Green Lantern's old nickname.



* In ''WesternAnimation/Ben10AlienForce'', Past Gwen demands Future Gwen say something only they/she would know. Future!Gwen whispers something to her, prompting a disgusted reaction. We never find out what it was. Dwayne [=MacDuffie=] refused to comment, saying it was "personal."

to:

* In ''WesternAnimation/Ben10AlienForce'', Past Gwen demands Future Gwen say something only they/she she would know. Future!Gwen whispers something to her, prompting a disgusted reaction. We never find out what it was. Dwayne [=MacDuffie=] [[ShrugOfGod refused to comment, comment]], saying it was "personal.""personal".



** In the sixth season finale, "To Where and Back Again", Starlight Glimmer and her team, venturing into a kingdom full of [[VoluntaryShapeshifting Changelings]], use the phrase "klutzy draconequus" as this. Discord isn't exactly pleased.

to:

** In the sixth season finale, "To Where and Back Again", Starlight Glimmer and her team, venturing into a kingdom full of [[VoluntaryShapeshifting Changelings]], use the phrase "klutzy draconequus" as this.a trust password. Discord isn't exactly pleased.



* On ''WesternAnimation/SouthPark'' Cartman wants to be a HumanPopsicle so he won't have to wait for the Nintendo UsefulNotes/{{Wii}} to come out. He ends up in a BadFuture (there is a war going on, but Cartman is mad he can't play the Wii) and calls his past self to fix things. He tries to convince his past self who he is by explaining that he drank Ovaltine and put Clyde Frog in the closet before going to Butters and trying to freeze himself. His past self merely thinks someone was spying on him.
* ''WesternAnimation/BatmanTheBraveAndTheBold'': In "The Criss-Cross Conspiracy!",Batman is trapped in Batwoman's body. Nightwing asks him to prove it by saying something only Batman would know. Batman responds "Your favorite color is blue, you used to sleep with a nightlight and you're deathly afraid of monkeys". Nightwing goes "It's him".
** Likewise, when Batman is [[ItMakesSenseInContext Astral projecting himself due to being buried alive]], he possesses Speedy and starts telling Green Arrow about what's going on, Arrow initially thinks it's Speedy doing an impression, then Bats grabs him by the hem of his shirt and threatens him to his face; "It really is you, isn't it?".
* In ''WesternAnimation/DynomuttDogWonder'', when Manyfaces has tricked Dynomutt into believing that Blue Falcon is an impostor, the hero proves himself by showing his friend that he knows Dynomutt's "one ticklish spot."

to:

* On ''WesternAnimation/SouthPark'' In ''WesternAnimation/SouthPark'', Cartman wants to be a HumanPopsicle so that he won't have to wait for the Nintendo UsefulNotes/{{Wii}} to come out. He badly overshoots his goal and ends up in a BadFuture (there is BadFuture, where there's a war going on, but Cartman is mad he can't play on which [[SkewedPriorities prevents him from playing the Wii) and Wii]]. He calls his past self to fix things. He things and tries to convince him of his past self who he is identity by explaining that things only he drank would know, liking drinking Ovaltine and put putting Clyde Frog in the closet before going to Butters and trying to freeze himself. His But his past self merely thinks someone was spying on him.
him and is not convinced.
* ''WesternAnimation/BatmanTheBraveAndTheBold'': ''WesternAnimation/BatmanTheBraveAndTheBold'':
**
In "The Criss-Cross Conspiracy!",Batman Conspiracy!", Batman is trapped in Batwoman's body. Nightwing asks him to prove it by saying something only Batman would know. Batman responds "Your know.
-->'''Batman:''' Your
favorite color is blue, you used to sleep with a nightlight night light, and you're deathly afraid of monkeys". Nightwing goes "It's him".
monkeys.\\
'''Nightwing:''' It's him.
** Likewise, when When Batman is [[ItMakesSenseInContext Astral [[AstralProjection projecting himself due to astrally]] after being buried alive]], BuriedAlive (ItMakesSenseInContext), he possesses Speedy and starts telling Green Arrow about what's going on, on. Arrow initially thinks it's Speedy doing an impression, then before Bats grabs him by the hem of his shirt and threatens him to his face; "It face.
-->"It
really is you, isn't it?".
it?"
* In ''WesternAnimation/DynomuttDogWonder'', when Manyfaces has tricked Dynomutt into believing that Blue Falcon is an impostor, the hero proves himself by showing his friend that he knows Dynomutt's "one ticklish spot."spot".



* In World War II: A variation of trust password is used to BluffTheImposter: The guard would state "The Land of the Free," to which an American would reply "And the Home of the Brave." Then the guard would state "The Terror of Flight," to which a German would reply as "And the Gloom of the Grave"... Every American soldier would know the first verse of their national anthem, but only a spy [[INeverSaidItWasPoison trying too hard to pass as one]] would know the ''third'' verse.
* According to tradition, UsefulNotes/JoanOfArc whispered some secret to the Dauphin to convince him that she had really been divinely inspired to help him claim the throne. According to additional tradition, what she whispers is that God wants him to be king of France, though some prefer to believe that she described an embarrassing birthmark on his backside. Another version holds that she repeated a prayer he'd said in private, which only God could have revealed to Joan.
* Magician Creator/HarryHoudini had spent much of his later career debunking mediums and others who claimed to speak "from beyond the grave". He arranged a number of code phrases (one being a song called "Rosabelle") as identifiers for his wife Bess if such communication was possible. He died in 1926, well before Bess. No one was ever able to deliver a message she was satisfied was genuine.
** Used well in Carrie Vaughn's Literature/KittyNorville series, where a medium contacts Houdini, and is told "Everyone who knew my codes is dead. No one will believe you. But thanks for trying".
** Reportedly most mediums who tried to contact Houdini's mother for him made the mistake of having her address him as "Harry" - which his real mother never would, because it was just a stage name. She would only ever have called him Erik. Also, his mother was a native Hungarian who would spoke better in that language and Yiddish than she did English.
* [[ThePasswordIsAlwaysSwordfish That password]] you have to tell the computer to make sure it's really you.
* Careful parents often arrange these with their children, so that the children can verify that anyone who claims to be sent by mom and dad actually was (as in the ''{{Series/Bones}}'' example above). Some [=PSAs=] (or similar productions) recommend this if the family ever gets separated.
* Surprisingly more common than most people think. It's extremely easy to set up, and it never hurts to be CrazyPrepared or GenreSavvy.
** There was a website many years ago (it's long since dead) that was touted as a "time-traveler's support network." Meeting places and times in various cities were designated where a "volunteer" from the project would wait for someone to say a one-time use passphrase and render aid. The database of locations, times, and phrases was said to exist in a sealed document held by a law firm which would be turned over to any time-travel project in the future.
*** It may be long since dead now, but if you're going back in time that shouldn't really be a problem.
* As in the ''Bourne'' example above, secret agents normally have security checks they can insert into a message to verify that it's real. During UsefulNotes/WorldWarII, one British agent captured in Holland by the Germans [[OutOfCharacterAlert deliberately gave his captors the wrong security check]]. He expected his bosses to realize that the messages coming from his radio were false. [[WhatAnIdiot His bosses didn't pay attention.]] Or they did pay attention but the agent was expendable to them anyway. ''Das Englandspiel'' (also called Operation North Pole) resulted in the capture and execution of approximately fifty Allied agents, and didn't end until the Germans themselves called it off in a clear-text message to London.
** This is also true of military operations. Generally speaking, rather than attempt to describe a situation, ground forces will have code phrases during extraction to describe the situation to the (usually a helicopter) extraction unit. The most common three types are Situation Under Control, In Contact, and Do Not Attempt Extraction. They're coded so that, if the ground forces have been captured, they can wave off the extraction unit without pointing out that they're doing so[[labelnote:*]]it's usually something that's incredibly innocuous, like a two-word code as shown in ''Bourne'': the pilot asks for authentication, and the ground troop says something like "Oscar Juliet", which is, on its own, meaningless to anyone else, but perfectly communicates the situation to the pilot[[/labelnote]].
* [[http://en.wikipedia.org/wiki/Shibboleth Shibboleths]] are words whose pronunciation is so unique that only native or extremely fluent speakers can pronounce them correctly.

to:

* In Trust Passwords are naturally commonly used in the military and to detect spies:
** A common way to accomplish this was with a [[http://en.wikipedia.org/wiki/Shibboleth shibboleth]], a word whose pronunciation is unique enough that only certain speakers can say it correctly. It's [[OlderThanFeudalism old enough]] for the term to come from Literature/TheBible. It was used commonly in UsefulNotes/WorldWarII, most deviously with the word "lollapalooza", which abused [[JapaneseRanguage the Japanese inability to pronounce the letter "L"]] to allow Americans to weed out Japanese soldiers.
** One
World War II: A II variation of trust password is was used to BluffTheImposter: BluffTheImpostor. The guard would state state, "The Land land of the Free," free", to which an American would reply reply, "And the Home home of the Brave." brave" -- an easy reference to the national anthem. Then the guard would state "The Terror terror of Flight," to which a German would flight", and if the reply as was "And the Gloom gloom of the Grave"... Every American grave", the guard knows it's really a German soldier would know the first verse of their national anthem, but -- because only a spy [[INeverSaidItWasPoison trying too hard to pass as one]] an American]] would know the ''third'' verse.
verse of the anthem.
** Secret agents are typically given several security checks they can insert into a message to verify that it's real. That said, they don't always work; a British agent captured by the Germans during World War II tried this, but his bosses didn't pay attention, and it led to ''Das Englandspiel'' (''a.k.a.'' Operation North Pole) and the capture and execution of fifty Allied agents. What's scarier is the possibility that the bosses ''did'' get the message but considered their cover more valuable than the agent's life.
** In modern military operations, ground troops will use code words to describe a situation to an extraction unit (usually a helicopter) rather than describing it outright; this allows them to call off an extraction if they're captured without tipping anyone off.
* According to tradition, UsefulNotes/JoanOfArc whispered some secret to convinced the Dauphin to convince him that she had really been divinely inspired to help him claim the throne. According to additional tradition, what she whispers is that French throne by whispering a secret into his ear. That secret ranges from a prayer the Dauphin had said in private (which Joan could learn only from God wants him Himself), to God wanting the Dauphin to be king of France, though some prefer king, to believe that she described describing an embarrassing birthmark on his backside. Another version holds that she repeated a prayer he'd said in private, which only God could have revealed to Joan.
backside.
* Magician Creator/HarryHoudini had spent much of his later career debunking mediums and others who claimed to speak "from beyond the grave". He debunked several mediums who tried to contact his mother and made the mistake of having her address him as "Harry" (which was his stage name, when she would use his real name, Erik) or speaking in English (when she was more confident in Hungarian or Yiddish). Houdini also arranged a number of code phrases (one being a song called "Rosabelle") as identifiers for with his wife Bess which he promised to use if such communication was possible. he died before her and tried to contact her after death. He died in 1926, well before Bess. No Bess, and no one was ever able to deliver a message she was satisfied was genuine.
** Used well in Carrie Vaughn's Literature/KittyNorville series, where a medium contacts Houdini, and is told "Everyone who knew my codes is dead. No one will believe you. But thanks for trying".
** Reportedly most mediums who tried to contact Houdini's mother for him made the mistake of having her address him as "Harry" - which his real mother never would, because it was just a stage name. She would only ever have called him Erik. Also, his mother was a native Hungarian who would spoke better in that language and Yiddish than she did English.
* [[ThePasswordIsAlwaysSwordfish That password]] you have to tell the computer to make sure it's really you.
* Careful parents often arrange these with their children, so that the children can verify that anyone who claims to be sent by mom and dad actually was (as in the ''{{Series/Bones}}'' example above). Some [=PSAs=] (or similar productions) was. [[PublicServiceAnnouncement PSAs]] also recommend this for if the family ever gets separated.
* Surprisingly more common than most people think. It's extremely easy to set up, and it never hurts to be CrazyPrepared or GenreSavvy.
** There was
separated. This is the basis for a website many years ago (it's long since dead) that was touted as a "time-traveler's support network." Meeting places and times in various cities were designated few fictional portrayals (like the ''Series/{{Bones}}'' example above), where the hero tries to save a "volunteer" kid in danger but needs the password from the project would wait for someone to say a one-time use passphrase and render aid. The database of locations, times, and phrases was said to exist in a sealed document held by a law firm which would be turned over to any time-travel project in the future.
*** It may be long since dead now, but if you're going back in time that shouldn't really be a problem.
* As in the ''Bourne'' example above, secret agents normally have security checks they can insert into a message to verify that it's real. During UsefulNotes/WorldWarII, one British agent captured in Holland by the Germans [[OutOfCharacterAlert deliberately gave his captors the wrong security check]]. He expected his bosses to realize that the messages coming from his radio were false. [[WhatAnIdiot His bosses didn't pay attention.]] Or they did pay attention but the agent was expendable to them anyway. ''Das Englandspiel'' (also called Operation North Pole) resulted in the capture and execution of approximately fifty Allied agents, and didn't end until the Germans themselves called it off in a clear-text message to London.
** This is also true of military operations. Generally speaking, rather than attempt to describe a situation, ground forces will have code phrases during extraction to describe the situation to the (usually a helicopter) extraction unit. The most common three types are Situation Under Control, In Contact, and Do Not Attempt Extraction. They're coded so that, if the ground forces have been captured, they can wave off the extraction unit without pointing out that they're doing so[[labelnote:*]]it's usually something that's incredibly innocuous, like a two-word code as shown in ''Bourne'': the pilot asks for authentication, and the ground troop says something like "Oscar Juliet", which is, on its own, meaningless to anyone else, but perfectly communicates the situation to the pilot[[/labelnote]].
* [[http://en.wikipedia.org/wiki/Shibboleth Shibboleths]] are words whose pronunciation is so unique that only native or extremely fluent speakers can pronounce them correctly.
parents.


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* And in general, more people than you'd think have trust passwords just because they're GenreSavvy, CrazyPrepared, or extremely nerdy. One old website was touted as a "time traveler's support network" which designated secret meeting places and times in various cities, where a "volunteer" would help anyone who used the correct password. The website is long since dead (not that this should be any problem for a time traveler anyway).
7th Feb '17 3:21:35 PM AnotherDuck
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** {{Inverted|Trope}} by GenreSavvy players in the comics. Often, players will set up a "Doppleganger Password"; should a character become separated from the group and later rejoin, they can be asked to provide the password in order to prove that they're not an infiltrator in disguise.

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** {{Inverted|Trope}} Used by GenreSavvy players in the comics. Often, players will set up a "Doppleganger Password"; should a character become separated from the group and later rejoin, they can be asked to provide the password in order to prove that they're not an infiltrator in disguise.
1st Feb '17 3:40:08 AM Zelnor
Is there an issue? Send a Message

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* [[spoiler: Gilthunder's supposed BadassBoast]] in [[Manga.NanatsuNoTaizai The Seven Deadly Sins]] turns out to be this. It's a phrase learned from Meliodas, to be used if they're ever in deep trouble.
-->[[spoiler:'''Gilthunder''': I am now stronger than any of the Seven Deadly Sins!]]
19th Jan '17 5:05:28 PM luord
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* ''Film/KingsmanTheSecretService'': After Eggsy's father's HeroicSacrifice, Harry Hart pays a visit to the deceased's family and gives Eggsy a medallion with a number they can call to request a "favor", along with a choice of words they have to say to the speaker.
--> "Oxfords not brogues."
13th Dec '16 5:44:34 PM eroock
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* In ''Film/EdgeOfTomorrow'', Rita devises one for Cage when he first convinces her that he can time travel, allowing him to quickly convince past her in subsequent loops. She also decides to reveal her middle name "Rose" to him, probably to make it even easier for him in subsequent "runs".
13th Dec '16 5:42:08 PM eroock
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* In scifigrl47's [[http://archiveofourown.org/series/18228 Toasterverse,]] Tony has one of the escaped scientists sing the Teapot Song to verify his hand in their escape.
* In the [[Fanfic/EakinsHardReset Hard Reset]] sequel [[http://www.fimfiction.net/story/145711/hard-reset-2-reset-harder Hard Reset 2: Reset Harder,]] when Celestia hears that Twilight is a fellow [[GroundhogDayLoop time looper]], she tells Twilight a password to unlock secret knowledge in Celestia's brain. When Twilight repeats the password to Celestia later on, [[spoiler:she's paralyzed by a powerful spell, and Celestia immediately kills her after revealing that the "secret knowledge" is the rest of the password. It's repeating the ENTIRE combination that convinces Celestia of Twilight's story]].
* In [[http://tvtropes.org/pmwiki/pmwiki.php/FanFic/Sols06sPhineasAndFerbVerse PnF: Stolen Identity,]] Phineas does an impromptu one on [[EvilTwin Ferb's replacement]], asking him about the day they first met. Different from the typical example in that the first time he asks this question, he doesn't realize he's talking to an impostor (rather he thinks Ferb's gone mad) and wants reassurance that Ferb is still the person he loves. Later the real Ferb answers the question (Phineas insisted on saving Ferb some cake if you're wondering) much to Phineas' obvious relief.

to:

* In scifigrl47's [[http://archiveofourown.''[[http://archiveofourown.org/series/18228 Toasterverse,]] Toasterverse]]'', Tony has one of the escaped scientists sing the Teapot Song to verify his hand in their escape.
* In the [[Fanfic/EakinsHardReset ''[[Fanfic/EakinsHardReset Hard Reset]] Reset]]'' sequel [[http://www.''[[http://www.fimfiction.net/story/145711/hard-reset-2-reset-harder Hard Reset 2: Reset Harder,]] Harder]]'', when Celestia hears that Twilight is a fellow [[GroundhogDayLoop time looper]], she tells Twilight a password to unlock secret knowledge in Celestia's brain. When Twilight repeats the password to Celestia later on, [[spoiler:she's paralyzed by a powerful spell, and Celestia immediately kills her after revealing that the "secret knowledge" is the rest of the password. It's repeating the ENTIRE combination that convinces Celestia of Twilight's story]].
* In [[http://tvtropes.''[[http://tvtropes.org/pmwiki/pmwiki.php/FanFic/Sols06sPhineasAndFerbVerse PnF: Stolen Identity,]] Identity]]'', Phineas does an impromptu one on [[EvilTwin Ferb's replacement]], asking him about the day they first met. Different from the typical example in that the first time he asks this question, he doesn't realize he's talking to an impostor (rather he thinks Ferb's gone mad) and wants reassurance that Ferb is still the person he loves. Later the real Ferb answers the question (Phineas insisted on saving Ferb some cake if you're wondering) much to Phineas' obvious relief.



* [[http://archiveofourown.org/series/82162 Stars From Home]]: When Hank's cure first works, Scott assumes the not-blue-and-furry Hank is a imposter. Hank tries twice before managing to convince Scott of who he is--because he knows why Scott doesn't like The Andy Griffith Show. A few chapters later, Charles has to prove his identity to Ruth when he uses Hank's serum to walk. His initial attempt at using personal details does not go well.

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* [[http://archiveofourown.''[[http://archiveofourown.org/series/82162 Stars From Home]]: Home]]'': When Hank's cure first works, Scott assumes the not-blue-and-furry Hank is a imposter. Hank tries twice before managing to convince Scott of who he is--because he knows why Scott doesn't like The Andy Griffith Show. A few chapters later, Charles has to prove his identity to Ruth when he uses Hank's serum to walk. His initial attempt at using personal details does not go well.



* In the Series Four ''Series/DoctorWho'' episode "Forest of the Dead," Professor Song [[spoiler: whispers the Doctor's name into his ear]] to prove that she knows him in the future.

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* ''Series/DoctorWho'':
** In the two-parter "Human Nature"/"The Family of Blood", Martha Jones, a medical student from the future, uses her knowledge of anatomy to prove that she's not "just" a maid, which she's currently disguised as.
**
In the Series Four ''Series/DoctorWho'' episode "Forest of the Dead," Professor Song [[spoiler: whispers the Doctor's name into his ear]] to prove that she knows him in the future.



* ''Series/DoctorWho'': In the two-parter "Human Nature"/"The Family of Blood", Martha Jones, a medical student from the future, uses her knowledge of anatomy to prove that she's not "just" a maid, which she's currently disguised as.
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