Cyclops: Prove it.
Wolverine: You're a dick.
[beat, Cyclops drops his hand]
The polar opposite of a Not Himself or Out-of-Character Alert; a character in disguise or otherwise hidden reveals themself to friends by saying something only they would say.
Undercover agents and victims of a Forced Transformation or a "Freaky Friday" Flip will occasionally use Something Only They Would Say to positively identify themselves. Also handy in figuring out which twin is the Evil Twin, or when you're in the middle of a Twin Switch (though just as often, it's keyed off of Out-of-Character Alert).
Sub-Trope of Trust Password, which is for general things to establish trust, instead of an utterance so specific to one person that it identifies just them.
Compare You Just Told Me, Ironic Echo, Cover Identity Anomaly, So Crazy, It Must Be True, Varying Competency Alibi, and Bluff the Impostor. No One Else Is That Dumb is a Sub-Trope. If it's something that anybody from a particular group or with specific knowldge can answer, that's Only the Knowledgable May Pass. Contrast Out-of-Character Alert where a character wants to remain unidentified but says the identifying phrase out of habit, which at best makes someone just a touch suspicious. Sometimes overlaps with Reflexive Response.
- Anime & Manga
- Comic Books
- Fan Works
- Films — Live-Action
- Live-Action TV
- Video Games
- Western Animation
- Jasmine is tipped off to Prince Ali's identity when he asks her, "Do You Trust Me?". He also rolls an apple down his arm and throws it to her with his elbow, a trick he does as both Aladdin and Prince Ali. The animator who drew Jasmine's facial expression when she realizes this deserves an award.
- The old man whom Aladdin meets in the dungeon says "prin-cess" like Jafar does. He's revealed to the audience to be Jafar immediately after, so most people don't even notice.
- Anastasia: During Anya's interview with Sophie, Sophie specifically asks how she escaped the siege on the Winter Palace. Vlad and especially Dmitri think the jig is up since they never prepared her for that question, only for Anya to remember a servant boy who "opened a wall". Dmitri immediately recognizes this because he was that servant boy, and realizes she's the real princess because she's one of only three people who would've known that. This happens again when Anya does finally get a chance to talk to Marie. Marie initially brushes her off as an actress, albeit "the best one yet". It's not until Anya recalls an intimate memory about spilling Marie's peppermint oil on the carpet and lying on that spot whenever Marie left the country that gets her to reconsider. Bringing out the matching necklace and music box and singing their lullaby seals the deal.
- In Barbie as the Island Princess, the only thing Ro can remember before she got amnesia is the song, "Right Here in My Arms". At the end of the movie, the Queen and Ro realize that they're mother-daughter because the Queen used to sing it to her daughter.
- Batman Beyond: Return of the Joker:
- The Joker introducing his return in Neo Gotham in front of an elderly Bruce Wayne. Bruce is in stunned disbelief, but his old arch-nemesis assures Bruce that it really is him because "after all, who'd know me better than you". This also foreshadows the flashback revealing that the Joker had managed to discover Bruce Wayne was Batman shortly before he was killed... the first time.
- Batman, gunning for the Joker near the end, runs into the ex-Robin Tim Drake instead. Before Batman can take him to a hospital, Tim addresses him by his secret identity, Terry McGinnis. Batman asks how Tim even knew that, before Tim calls him by another name: "Batfake", the Joker's pet handle for the current Batman. Tim then proceeds to transform into the Joker.
- Syndrome in The Incredibles tells Mr. Incredible "I am your biggest fan...", which makes Mr. Incredible realize Syndrome is actually the grown-up Buddy Pine.
- In Megamind, everyone calls the setting Metro City except for the title character, who pronounces it to rhyme with atrocity. When he's fighting Titan disguised as the superhero Metro Man in the climax, he accidentally gives himself away when he mentions the city's name. The only reason Titan knows this is because he heard Megamind say it dozens of times as a news cameraman.
- A non-verbal version happens in The Lion King (1994). When Simba fights a lioness that was trying to eat Timon and Pumbaa. Simba is eventually defeated by the lioness when she uses Nala's trademark flip-and-pin move on him, the same one that Nala used to beat him when they were cubs. This causes Simba to realize the lioness he is fighting is actually his best friend Nala.
- Red Shoes and the Seven Dwarfs: Merlin, while fighting a giant tree monster, makes a remark about how it's more block-headed than Prince Average. The monster roars "Av-Ooh-Raj!" in response, causing Merlin to realize that it's actually a transformed Average, since he's the only one that pronounces his name like that.
- In Reign of the Supermen, when Lois confronts the returned Superman following his Dynamic Entry, she asks what was the last secret he told her before he died. It was "I love you".
- In The Secret of NIMH 2: Timmy to the Rescue, when they were kids, Martin, jealous that Timmy was the prophesied hero of Thorn Valley and not him, derogatorily called his brother "Hero". Years later, when Timmy reunites with Martin, who had become hyper-intelligent and took over NIMH, he recognizes him through his changed appearance when he says...
Martin: I suppose I have changed a bit. But for the better, don't you think, hero?
- A non-verbal example occurs in Toy Story 2. When the other toys are confused about which of the two Buzz Lightyears is their friend, the "real" one merely lifts his foot to reveal the name "Andy" written on it and opens the other one's helmet, which immediately causes the "imposter" to gasp for breath. The toys all happily exclaim "Buzz!" as they rush to hug their friend.
- In The Transformers: The Movie, after Megatron's death, people are suddenly surprised by the arrival of a new, purple-and-black robot who crashes Starscream's coronation. Then he opens his mouth and smugly demeans the Decepticon's new leader before easily killing him.
Starscream: Who disrupts my coronation?!
Galvatron: Coronation, Starscream? This is bad comedy.
Starscream: ...Megatron? Is that you?!
Galvatron: Here's a hint! [transforms into a laser cannon and reduces Starscream to ash]
- 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.
- It's believed that the Japanese custom of answering the phone with "moshimoshi?" was to affirm the speaker as human. Supposedly, Kitsune would be unable to pronounce that phrase.
- Older Than Feudalism: In The Four Gospels, after Jesus comes Back from the Dead, not all of his disciples recognize him right away. On one occasion related by Luke, he walks and talks with two of them all the way from Jerusalem to Emmaus, and they don't realize who they are talking with until he prays before a meal — apparently, the prayer was something only he would say. (Then, as soon as they recognize him, he disappears.)
- Based on the context, the words in question were most likely, "This is My Body."
- Luke specifically says that Jesus gave thanks and broke the bread, which is how he described what happened before he said "This is my body" at the Last Supper, so a common interpretation is that the way Jesus broke the bread was distinctive.
- In Red Panda Adventures, when the Flying Squirrel is hypnotized to believe that the enemy they're fighting is the Red Panda and the Red Panda is the bad guy, the Panda proves his identity by whispering "Kit Baxter, behave yourself!" in her ear.
- Unwell Podcast: A variant happens in season five. When Dot Harper is faced with two Russell Epsteins, she asks them both what her first music record was. The fake Russell, an aspect of Fenwood House, is the one who knows the real answer.
- In Dawn of a New Age: Oldport Blues, Ivy comes across her best friend Luna while the latter is being imbued with her superpower and spouting electricity from every orifice. Convinced that she's some monstrous imposter, Ivy runs away. Luna catches up to her, and Ivy realises that she's the real Luna when she bluntly tells Ivy to 'nut up and stop being a pussy'.
- Ace Attorney:
- Iris reveals that she was the "Dollie" Phoenix dated in college by referring to him by the nickname "Feenie", which "Dollie" gave to him when they were dating.
- It's for the players' benefit instead of the characters, but one of the escalating hints that Diego Armando is Godot is that he says "that's one of my rules", which is one of Godot's catchphrases.
- Downplayed in Nine Hours, Nine Persons, Nine Doors. Junpei recognizes that the girl he met was someone he knew, but only realizes who exactly she is when she calls him by Affectionate Nickname "Jumpy", only used by his childhood friend Akane.
- In Dominic Deegan: Oracle for Hire, Gregory is disguised as "ace reporter Buzz Beardman"... but Rachel recognizes him right away when she hears the name, because Gregory created Buzz Beardman as a character in a comic book he made as a child.
- Klo Tark's spirit identifies himself by mentioning "he who I would call my brother", his last words as a living person, to Dominic, the person he was referring to with said last words.
- In The Order of the Stick 397, Nale identifies himself as the Evil Twin by responding characteristically to an insult directed at his Evil Plans.
- This same trait is later used in an inversion of this trope: Part of Tarquin's evidence that Elan is not Nale is that Elan did not ramble about his intellectual superiority, which Nale would have done.
- Subverted the first time Vaarsuvius's familiar, Blackwing, speaks to Roy and Belkar.
Belkar: It can talk?!?
Roy: No, probably not. I think it's probably some sort of magical message [...]. Those were V's words, just coming out of the bird's beak.
Blackwing: You are both ignorant cretins.
Belkar: Yeah. I guess you're right.
- Inverted in another instance. When Roy is fighting the Vampire Durkon his opponent taunts him over his younger brother's death, even asking how many pieces the body was in. This is so uncharacteristic of Durkon that Roy realizes that Durkon either suffered a Death of Personality upon becoming a vampire or is suffering Demonic Possession.
- Bob and George: Don't say "What?" in response to your name if you want to go for Implausible Deniability.
- In Sluggy Freelance, not so much Something Only They Would Say as Something Only They Would Do. Upon his return from an alternate dimension, Torg hugs Bun-Bun. This results in the inevitable beating. At first, the other characters think this proves he isn't their Torg, since their Torg would've known Bun-Bun would beat him up over that. However, they then realize it was their Torg because he seems happy about getting beaten up, and only he would do something so stupid as use Bun-Bun's aggression to determine whether he's in the right dimension or not.
- In this xkcd strip, someone discovers that babbling enthusiastically about foolproof ways to establish his identity is apparently sufficient to establish his identity.
- The Alt text makes it even better:
"Not sure why I just taught everyone to flawlessly impersonate me to pretty much anyone I know. Just remember to constantly bring up how cool it is that birds are dinosaurs and you'll be set."
- The Alt text makes it even better:
- Girl Genius: Higgs is questioning the identity of the fragment of the Castle stuck in dingbot form up until it gleefuly orders him to murder Tarvek.
Tarvek: You'll notice it's got every bit of the castle's usual charm.
Castle: Now, that is certainly true! General? Kill him and let's be off.
Higgs: Yep. That's the castle.
- In Gunnerkrigg Court, the Annie who spoke to Loup convinces Winsbury and Janet she's real because she knows they're a couple. At this point, all the evidence suggests both Annies are real, though, or least until a weird flame spirit thing tells them both of them are in the wrong timeline, so there likely is another Annie somewhere.
- The trope is subverted in the Housepets! storyline "My Life as a Teenage Squirrel", when Marion, a male human teenager who woke up as a female squirrel is trying to explain this to his girlfriend, she asks if she's expected to believe this, and he says no, it's utterly unbelievable and nothing he can do or say could prove it. She suggests telling her something only Marion would know, and he describes what was clearly the most embarrassing experience of his life. However, the logically-minded Lois still finds the very idea of such a transformation so unbelievable that she immediately jumps to a more "rational" conclusion instead.
Lois: …Marion told you about that.Marion: You see?!
- Marion gets his revenge later on, by popping this same question when Lois has been transformed into a bobcat herself, right before Marion's eyes.
Lois: I swear I will eat you.
- Marion gets his revenge later on, by popping this same question when Lois has been transformed into a bobcat herself, right before Marion's eyes.
- Out-of-Placers has Kass undergo a Forced Transformation early on. Resident 'medic' Galen doesn't buy it until he's roundly and articulately insulted by the now-yinglet Kass.
Galen: What, that's Kass? No it isn't. Quit being stupid.
Kass: Galen, you are a pazetic smoke-spitting loser who hasn't done any real medical work since za war and I wouldn't let you help me even if you could. You ass.
Galen: Holy shit! Kass! Whadda they done to ya!?
- Saturday Morning Breakfast Cereal: Parodied here when a man proves to his wife that he is her real husband by pointing out the acne on her butt. She guns him down and and takes the robot as her husband.
- In the Paradise setting, a number of people who have been involuntarily Changed into Funny Animals use this method to convince friends and loved ones that it's "really them".
- In Qwerpline Derek's voice changes and Alex asks him a series of questions (over the phone) to try and confirm his identity. The fact that Derek completely fails to answer any of the questions convinces Alex that it's actually him.
Alex: "Tell me what Gus' new tattoo say?"
Derek: "I don't know, I can't read Japanese."
Alex: "Oooh, Okay, Possible Derek. How many nipples does Michael O'Leary have?"
Michael: "The answer, gentle listener, may surprise you."
Derek: "Oh come on! Everybody knows that! He won the contest!"
Alex: "Okay... How about this: What does the poster in the recording studio say?"
Derek: "That's a dirty trick! You know I can't say those 8 words on radio!"
Alex: "AAAAAH! IT'S DEREK!"
- In Sonic Limited Edition: The Lost Cartridge, James briefly mentions "the sock" to convince Ned that it's him in "The One on the Phone."
- The concept of the shibboleth, a way of identifying someone as an ally as described in the Book of Judges, where captured Ephraimites are betrayed by the fact that they can't pronunce the "sh" phoneme and would say "sibboleth" instead, is based around this. These days, shibboleths are call-and-response; a belligerent in a war will have a certain phrase and counter-phrase. If an approaching battalion gets the phrase wrong, they're the enemy. If the guard gets the counter-phrase wrong, the outpost is under enemy control. Examples include:
- During the invasion of Normandy, the Americans would open with "Flash," counter with "Thunder," and confirm with "Welcome." This hinges on the fact that a German would pronounce it "Velcome," and caused problems for some German paratroopers that defected, as well as some German- and Yiddish-speaking Jews who had fled German rule and joined the US Army.
- A British variant in the invasion summer of 1940 would have been, for the same reasons, constructed like Weymouth War Weapons Week
- American POWs in Vietnam communicated by tapping Morse code on their cell walls. One would initiate a conversation by tapping the familiar "Shave And A Haircut" pattern, and the other would finish with "two bits". If the respondent instead repeated "shave and a haircut", it meant he was a Vietnamese agent.
- When Americans were being evacuated from Saigon, American newsman Ken Kashiwahara was afraid of being mistaken as Vietnamese and left behind, so he planned to say "I'm from Los Angeles, and the Dodgers won the pennant" if that happened (it didn't).
- English rioters during the Peasants' Revolt went around looking for Flemish weavers to beat up, identifying them by demanding people say "bread and cheese", which the Flemings did with a distinctive accent.
- About eighty years previously, the Flemish used "Schild en Vriend" (shield and friend), which the French who they were revolting against could not pronounce, making it Scilt, so the Flemish knew who to butcher.
- Sectarian fighters in Northern Ireland can supposedly identify whether someone is a Catholic or a Protestant depending on how they pronounce the letter H (Protestants would call it aitch while Catholics would call it haich).
- Shibboleths need not be confined to wartime or otherwise violent situations. A lot of Swiss people have a habit of making any and all foreigners say 'Chochichäschtli' (a small kitchen cupboard). Not only is it rather difficult to get all these 'ch' sounds right, even if people do, they usually have trouble pronouncing the vowels the correct way. However, if someone is Welsh or Scottish, they usually manage pretty well.
- Unexpected pronunciations of local place names can out someone as not being from the area, even if accent isn't an issue.
- If you're in New York City and don't want to be identified as a tourist, don't pronounce Houston Street like the city in Texas. Pronounce it like "HOUSE-ten" - the street name is a corruption of William Houstoun, who represented Georgia at both the Continental Congress and the US Constitutional Convention (the street used to be part of his father-in-law's estate).
- Natives of Austin, Texas can usually tell if someone is new to the city (or a tourist) by how they pronounce Manchaca note Road.
- It's easy to tell who has spent some time in the state of Hawaii in both verbal and written ways. When it comes to the written form, it's people who are diligent about including the ʻokina in applicable words, given that the ʻokina is considered part of the Hawaiian alphabet, meaning that the state is properly spelled "Hawaiʻi". Verbally, they account for the glottal stop the ʻokina represents (similar to the way "tt" is pronounced in a Cockney pronunciation of the word "bottle"), and they pronounce Ws as Vs in Hawaiian words. So, where the normal person would say "huh-WHY-yee", the native or longtime resident would say "ha-VAH-ee".
- A few examples from the Pacific Northwest: Oregon (locals pronounce it "OR-uh-gun", not "OR-uh-gone"), Willamette ("wa-LAM-et", leading to the rhyme "Willamette, dammit!"), and Couch Street ("Cooch Street"). Pronouncing any of those wrong is a dead giveaway that you're not a local.
- Florida is full of towns with oddly pronounced names that seem designed specifically to confuse people from out of state. Immokalee (Ih-MAH-kuh-lee), Interlachen (In-ter-lock-en), Matlacha (MATT-luh-shay), Rio (RYE-oh), and so many others.
- Mobile, Alabama. The name is French and pronounced "Mo-BEE-uhl" by the locals.
- FBI turncoat Robert Hanssen was caught this way. After several US agents had been captured and executed by the Soviets, the Bureau knew they had a mole on their hands. No one suspected Hanssen, however. He was even tasked with finding the leaks for a time. Eventually a communique between Hanssen and his handlers was intercepted, but there was no way to tell who the mole was —until an agent recognized a racial slur the mole made as something only Hanssen would say.note
- Former dictator of the Dominican Republic Rafael Trujillo decided that he didn't want any Haitians in his country (the Dominican Republic and Haiti share the island of Hispaniola). So, he had his agents show parsley to people near the border and ask them what it was. The Spanish speaking Dominicans would be able to pronounce the Spanish word 'perejil' ('parsley') properly, while French speaking Haitians would not. Those who couldn't were usually killed and it's estimated that there were between 20,000 and 30,000 deaths in the "Parsley Massacre".
- A Finnish shibboleth during the WWII was Höyryjyrä ("steamroller"). The voiced 'h', frontal 'ö' and 'ä' phonems, labial 'y' and rolling 'r' are almost impossible for anyone except native Finns to pronounce.
- Likewise, the name of the town of Jyväskylä would be nigh impossible for anyone but a native Finn to pronounce.
- One test used by Americans during WWII to tell if someone was a Japanese spy was to ask them to say the word 'Lollapalooza'. The trouble native Japanese have with the letter L was used to good advantage.
- An Australian accent can be difficult to reproduce without practice, so if you really wanted to know if someone is from Down Under, asking them a simple question, like to say 'How are you going' can often reveal them, as they will most like say something along the lines of 'How ya garn'. And if you ever ran into someone with a great fake Aussie accent, getting a genuine Aussie to check the slang (even small ones like mate, arvo [afternoon], servo [service station] or other slang words) they use.
- Ted Kaczynski was exposed as the Unabomber by his brother David when the latter read the Unabomber Manifesto and found not only similar themes to an essay Ted wrote in college but also the sentence "You can't eat your cake and have it, too" as opposed to the usual idiom "You can't have your cake and eat it too". David had only ever heard that alternate phrasing used by Ted and his mother.
- Want to know if someone's from Chicago? Just ask them if it's "Too haht for hackey."
- Before he died, Harry Houdini promised his wife that he would try to contact her from beyond the grave and set up a secret phrase he would say to verify his identity and counteract frauds. His wife held yearly seances after his death but none of them produced the secret phrase.