Alice, Bob and Claire all speak Language A, which is usually the language the work is written in or translated into, and may be the "common" language of the world. But Alice and Bob also speak Language B, which may be their native language, while Claire does not, enabling them to have private conversations if Claire is in earshot or they know Claire is eavesdropping.
To qualify, Alice and Bob must also speak a language Claire can speak, and Claire's inability to understand the language must be her only obstacle to understanding it; if she's deaf and unable to read lips, it doesn't matter whether she can speak Alice and Bob's language.
This trope can also be used to keep information from the audience, depending on whether a translation is provided. If the language is real and not translated, it can be a Bilingual Bonus.
This trope can be subverted if, unbeknownst to Alice and Bob, Claire knows the language they are using, leading to a Bilingual Backfire. See also Censorship by Spelling which uses similar methods to achieve the same goal. If Alice and Bob also pretend not to know Language A, they might use a Completely Unnecessary Translator.
Subtrope of Language Barrier. If this is done just to tease and intrigue Claire, it is Teasing from Behind the Language Barrier. If Alice and/or Bob pretend to not know Claire's language because they simply don't want to talk to her, it's Language Fluency Denial. See also Reality Has No Subtitles.
- Mahou Sensei Negima!: At one point, Yuuna's father is meeting a woman to discuss business. Yuuna and her friends assume he's on a date and decide to follow and watch. However, despite both being Japanese, they hold all their conversations in English (both because they're discussing magical matters and because they've noticed Yuuna's group following them).
- Since she started doing standup in the US, model/dancer-turned-comedienne Aiko Tanaka has gotten pretty good at using her thick Japanese accent for Asian Speekee Engrish humor. One of her jokes involves an ex-boyfriend in Los Angeles who wanted her to speak Japanese to him. At first she tells him to go hang out in Chinatown, because he wouldn't know the difference anyway, but she finally breaks down and rattles off a long sentence in Japanese. He finds it very arousing until she translates it to English, "I'm only with you for the Green Card."
- Dogbert's Clues for the Clueless gives insulting people in a foreign language they can't understand as an example of rude behavior — not quite as rude as saying "ucket-bay ead-hay," though insulting them in plain English is still worse.
Foreign Speaker #1: Xmphlaca bi flucalaka un bijnana y aquaholder.note
Foreign Speaker #2: Gne!
- Wonder Woman (1987): During Artemis's first outing as a hero at the end of The Contest she and Diana discuss how the last enemy to face them was a magical construct in their native langue, which annoys the police officers and reporters nearby who try to get them to talk in English.
- Red Hood: The Lost Days: Jason's teacher Egon tries to prevent Jason from learning about the fact that he sells child slaves on the side by making sure anytime it's mentioned somewhere Jason could overhear it's spoken about in German. Jason was however only faking his lack of knowledge about German and he kills Egon and everyone else involved in the trafficking.
- In Savior of Demons, Haabu attempts this in chapter 23, but is shut down in short order by Bulma and an irritated Frieza.
- In A Complete Turnabout, Edgeworth and Franziska have a conversation about Franziska's past in German front of Phoenix, who only knows enough German to realize that Franziska does not like him eavesdropping.
- In How to Survive in Middle Earth When You're a Teenaged Girl, for a moment in book 1, chapter 13, Priscilla speaks English to prove that she is a foreigner. The characters of The Lord of the Rings have no knowledge of English.
"I'm from a different world, y'all," I said flatly. "If you don't like it, that sucks for you. I'm also the only person who knows right now that everything's going wrong, and I'm the only person who can fix it. So you better start liking me real quick before I decide I've had enough and go off on my own."
- Marks of Time, chapter 24, has a scene where Lyla speaks Russian with a woman from Moscow. They pretend to talk about Fort Collins. The real topic is a man with them, who understands English but not Russian.
- The one-shot Lost in Translation revolves around Al's annoyance that his brother and his lover Noa enjoy doing this. No one on their side of the Gate understands either French or Romani, which Edward and Noa milk mercilessly. Al convinces Ed to teach him French for espionage reasons, but Ed still keeps Romani for him and Noa alone.
- Blind Courage: Impa knows rudimentary Gerudo from spending time amongst Gerudo. She uses this to her advantage when she talks to Ganondorf around his daughter Baby (who only understands Hylian).
- In The Demon Who Lived, the reincarnated Lelouch, Kallen, and C.C. are the only people in the world who speak Britannian English, something Kallen's new parents remark is closer to Welsh with German and Latin influences than English. When they first meet again, Kallen and C.C. quickly delve into speaking Britannian English, initially it's a test to make sure C.C. is the real deal and not just a cosplaying fan, but it's handy to keep Kallen's mother from learning she was in a sexual relationship with another woman.
- Blackbird (Arrow): After Laurel's freedom from the League is secured, but she isn't ready to open up to anyone, Diggle takes advantage of the fact that only the two of them speak Arabic to have a private conversation with her.
- Assassins. Psychotic hitman Miguel Bain brags about all the people he's killed to a couple of local vendors who only speak Spanish. The scene fits his reckless nature.
Miguel : I love cemeteries. One day you're here and the next you're down there — you know I put a lot of people down there. [laughs and the two vendors politely laugh with him]
- In The Boondock Saints II: All Saints Day, Romeo speaks Spanish to his uncle to ask him not to embarrass him in front of the MacManus brothers. He doesn't realize they know Spanish too.
- In Braveheart, Lord Hamilton attempts this using Latin during the first conference between Wallace and the Princess, assuming a Scotsman wouldn't speak or understand Latin. It doesn't work, since Wallace speaks both Latin and French.
- China Seas: The Malay pirates don't speak English. So, while smiling cheerfully and acting like he's trying to talk to the Malay chief, Gaskell actually yells to Davids the location of the bombs that they will use to counterattack the pirates.
- In Close Encounters of the Third Kind, Neary complains about this when Lacombe speaks to Laughlin in French.
- Cries and Whispers: When Anna refuses the offer of a memento of Agnes', Fredrik disdainfully comments that she's putting on a noble front but she'll get nothing from it. He says this in German so that Anna won't understand what he's saying about her.
- In Desperate Journey, Gestapo Major Baumeister does this sometimes when talking with his underling. Baumeister doesn't want anyone else to know that the Allied pilots who escaped from his office also managed to abscond with some sensitive classified documents.
- Done again (by the same actor, Christoph Waltz) in Django Unchained, when Schultz, a native speaker of German, takes advantage of the fact that Damsel in Distress Broomhilda speaks German so that he can tell her of the plan to rescue her without worrying whether anyone else is listening in.
- In Dragon Blade, very few characters are capable of speaking multiple languages in the movie (with Chinese and Latin (using English as stand-in) being most prominent, since the film is mainly about Chinese and Romans, but with background characters from other nations appearing from time to time). This allows the main character Huo An to openly plan a way to escape with his team in front of the Roman soldiers, who don't understand Chinese.
- Ex Machina. Nathan says that his Japanese maidservant doesn't speak English as a precaution against her overhearing any secrets. This may be a lie however, as she turns out to be a gynoid built by Nathan, and may be The Speechless.
- The Garden of the Finzi-Continis: Giorgio's parents are Italian but they speak in French when they don't want the maid to hear. And since this is Fascist Italy cracking down on Jews, sometimes they don't want to be overheard.
- Played with The Guns of Navarone. After Captain Miller has to abandon a wounded member of their commando team to be tortured by the SS, he pours out his angst to the mute Greek woman who's accompanying them. Turns out she can understand English quite well and speak it too, as she's The Mole for the Germans.
- Indiana Jones and the Temple of Doom: During the final confrontation against Mola Ram and the Thugees on the rope bridge, Indy managed to convey his plan to sever the bridge (with everyone on it) to his Chinese sidekick Short Round, using Mandarin.
Indy: "Xiao zi, zhuo zhu sheng zi!" note
- In Inglourious Basterds, the Jew Hunter speaks in English so the French-speaking Jews hiding under the floorboards can't understand what he and the farmer are talking about.
- Early in John Wick, a Russian mafia member attempts to impress John and threatening him of stealing his car by speaking in Russian. He isn't as pleased when the latter answers him in the same language.
- Looper. Joe is learning French so he can move to Paris when he retires. A time traveler advises him to go to China. Later Joe meets his older self from the future, who says he never regretted learning French even though he went to China instead. He asks how Joe's lessons are going, then says in French that he knows Joe has a gun between his legs.
Old Joe: Never mind.
- Attempted in The Lord of the Rings: The Two Towers, when Legolas tells Aragorn in Elvish that Helm's Deep's defenders are outnumbered and will die, but Aragorn angrily yells in Common that he will die along with them before storming off.
- Madame Rosa: Everybody in the movie is French, but Nadine and Ramon start talking to each other in English when they want to discuss Momo's highly agitated state.
- Dark Blue World (2001). Two Czech Spitfire pilots openly discuss the breasts of a British woman one of them is seeing, right in front of the woman in question.
- Max Manus. Max encounters a German sailor who shares a bottle with him, but doesn't understand when Max speaks to him in Norwegian. Somewhat drunk and stressed-out over the recent death of a friend, Max ends up delivering a Foreign-Language Tirade about his work in La Résistance.
- In Mission: Impossible Ghost Protocol, a Russian character tells his wife in English that they need to get out of the country after the Kremlin bombing. His son, who's in the room, asks them why they're talking in English.
- Murder on the Orient Express (2017). While interrogating the maid of an aristocrat, Poirot has her speak to him in German so her employer can't understand and influence her responses.
- A scene in My Fellow Americans does this. James Garner's character (an ex-President), and Jack Lemmon's character (also an ex-President) are on the run from assassins and hiding in a truck full of illegal immigrants (It Makes Sense in Context, sorta). While there Garner strikes up a conversation with one of the immigrants in Spanish, finally making some insulting remarks about Lemmon. As the punchline, after the two part company with the immigrants, Lemmon respons in flawless Spanish, "I can speak Spanish too, dickhead!"
- Oddly averted in Shanghai Knights. Chon Wang has a private conversation with his sister about Roy without knowing that Roy is eavesdropping. For some reason, they have the conversation in English rather than their native language, which Roy would not know.
- In The Shape of Water, Elisa boldly signs "Fuck you" to Strickland, knowing that he can't read sign language. Strickland does at least sense that he's being insulted, and Elisa's triumphant smirk implies that it's intentional on her part; she wants him to know he's being insulted, but be unable to prove it, and thus helpless to punish her.
- Likewise in The Last of the Mohicans. Duncan Heyward, an English officer, suspects that his Huron scout is back-chatting him, but can't prove it.
Heyward: You there! Scout. Must. Stop. Soon. Women. Are. Tired.Magua: Three leagues. Better water. We stop there.Heyward: No, we stop in the glade ahead. Understand?Magua: (subtitled) Magua understands the white man is a dog to his women. When they grow tired, he puts down his hatchet to feed their laziness.Heyward: What did you say?Magua: Magua said, "I understand English... very well."
- The Two Popes: During a private meeting with Cardinal Bergolio, Pope Benedict XVI notes that when he has to make hard and tough announcements, he will deliver them fully in Latin. This is because only about 20% of his Cardinals understand Latin fluently and so only 20% will understand what he has said while others struggle to catch up. True to this, when he announces his resignation from the Papacy, it is in full Latin and over half of the Cardinals present turn to the other asking if they just heard what they think they heard.
- Pretty much the whole point of the movie Windtalkers. Based on real-life events; in both World Wars, the American military in some cases obfuscated codes by having speakers of Native American languages such as Navajo and Cherokee relate them. Even if the enemy found someone would could understand (for example) Navajo, they'd still have to break the code itself. If transmitted in English an enemy codebreaker (who might be expected to know English) could reasonably guess that "turtle" might refer to a tank, but if you don't know what the world for "turtle" is and can't even pick it out of what is (to you) a stream of gibberish, your task as a codebreaker just got significantly harder.
- The Old Guard. When Nile tries at gunpoint to force the Russian pilot of the smuggler plane to land, Andy says something in Russian and then shoots the pilot herself, forcing Nile to untie Anya so she can fly the plane. Then the pilot sits up in his seat unharmed, Andy having told him to play dead when she fired the shot.
- The Alice Network: Lili, Violette, and Eve are spies who all speak fluent French... but since they're in France, any number of people who could overhear them speak French, and so they always communicate in English as a safeguard against the content of their conversation blowing their covers. English is considered "safe" because there arent many French and German people who speak it.
- Seen in Shanghai Girls. Pearl and her parents speak Sze Yp — a Chinese dialect, but her younger sister May does not speak this dialect. When Pearl and May end up in Chinatown in the US, this language barrier prevents May from talking to the family she has married into, and pushes her out into the broader world.
- In Dune, the deadly Count Fenring and his wife make heavy use of Obfuscating Stupidity, including punctuating their speech with lots of drawn-out hmmmmmmmmmmmmmms as an apparent Verbal Tic. When the book switches to their point of view, it turns out the humming is a code language to let them privately converse and coordinate their act in full view of everyone.
- One of the earliest scenes in The Night Circus is Hector and Alexander (presumably) issuing the challenge to pit Celia against one of Alexander's students... while Celia is standing right there. They pull this off through magic talk, but Celia cannot understand the adults while they converse and is oblivious to the topic of discussion.
- In The Great Brain at the Academy, Tom is sent to a Catholic Boarding School for 7th grade (the town only has a 1-6 One Room Schoolhouse). Tom's brother Sewyn is there in the 8th grade class and takes delight in hazing Tom and the other 7th graders (as he was presumably hazed when he was in the 7th). At one point early in the book Sewyn exposits to another 8th grader, "Remember, speak in Latin when we don't want the 7th graders to know what we're saying." [Because the 8th graders had learned Latin when they were in 7th but the new 7th graders hadn't learned it yet.]
- One of the CSI NY tie in novels has a subversion, with Stella and Lindsay processing a scene at a bakery. The owner thinks he's getting away with calling them a derrogatory Italian term for a female cop, but Stella speaks a little Italian, and though she's rusty, she knows exactly what he's saying.
- In one of the Ender's Shadow sequels, Bean and Petra are taking a cab in Armenia and start speaking in Portuguese (they had previously spent some years in Brazil). Bean points out that they're being very rude to the cab driver.
- In the Warcraft Expanded Universe novel, Lord of the Clans, another orc tries to tell Thrall "Run! I will protect you!" in Orcish, but Thrall, who doesn't know Orcish, does not understand what he says until someone tells him later, and neither does the reader.
- This appears in Jules Verne's 20,000 Leagues Under the Sea, as the crew of the Nautilus communicate among themselves in a secret language they invented to keep outsiders out. One of the crewmen breaking down and asking for help in his native language, revealing himself to be a Frenchman like Professor Aronnax himself serves as a significant plot point.
- Happens in The Bible, when the Assyrians are besieging Jerusalem. The Assyrian officers who come with surrender terms are asked by the Jewish commanders to converse in Aramaic, since most of the common folk don't understand it. However, at least one Assyrian knows Hebrew and shouts his "surrender or die" boast — listing what fates have befallen Assyria's previous enemies — loudly and in Hebrew so that all the defending soldiers will hear it too.
- In Sergey Lukyanenko's Seekers of the Sky duology, two characters try to converse in Gallic (French) while being given a tour of Aquincum (Budapest) by a local young man. Halfway through the conversation, he asks them in flawless Gallic if they'd like him to step away, so that they may continue their conversation in private. It turns out that the kid is an Omniglot, speaking eight languages while teaching himself a ninth.
- The German book Mordswiesn has half-Italian Bellina telling us that she enjoys being foreign because it means that whenever she's stopped by the police, she can pretend she doesn't speak German.
- The three members of Able Team (a Heroes "R" Us action series from the 1980's) would speak jive (or sometimes bad Spanish) when they wanted to exchange information without English-speaking foreigners being able to understand them.
- "Pas devant le..." is played with a couple of times in Discworld novels.
- In Making Money, Vetinari says "Pas devant le gendarme" to Moist, and Sergeant Detritus helpfully explains "Dat means no talkin' in front of me."
- In Unseen Academicals, one of the wizards snaps "Pas devant la domestique" to another when he mentions Archchancellor Bigger's Bequest in front of Glenda, the Night Kitchen cook. Ridcully reflects that Glenda looks like someone who's suddenly very keen to learn Quirmian.
- Deconstructed in the Lord Darcy novel Too Many Magicians, when they find a secret letter written in Polish. Darcy observes it's unlikely to have been written by an actual Polish spy, partly because the vocabulary is limited, and partly because a native speaker would not consider Polish a "secret language".
- In The Clay Pigeons of St Lo the US troops use American slang, but only discover after the war that the Germans can understand it better than they think, as there were Germans who grew up in the United States listening to their radio communications.
- Richard Hannay and Peter Pienaar, who have a shared background living in South Africa, converse in Cape Dutch (or Sesutu, if there might be Dutch speakers around) to keep the content of their conversation secret.
- Sandy Arbuthnot and another Scottish officer have a brief conversation in English but with an impenetrably thick Scottish accent while surrounded by people who, if they know English at all, have enough trouble with standard pronunciation.
- Much used in Fortune De France. Scholars speak Latin when commoners are around, Pierre and Miroul speak their Occitan dialect when in Paris, and they often use Italian or English for the same reasons.
- The Sack is an alien that has lived for so long it can answer any question. As every conversation with the Sack is monitored by the government, a criminal turns up wanting to know how to kidnap the Sack but phrases the question in an obscure Martian dialect. By the time anyone asks the Sack what he wanted, the plan is already in motion.
- A German Requiem: Bernie Gunther, a German, has engineered his fake arrest by the Russians in Vienna in order to gain the trust of Lotte, another German. He and Capt. Rustaveli of the Russian police discuss this, in Russian, right in front of Lotte.
- In the first season of 24, Jack and a police officer are pursuing a suspect, when they see a bystander and the officer yells in Spanish for the bystander to get down. The suspect takes the officer hostage, and Jack yells for her to fight back in Spanish. The suspect is captured but the officer dies in the process.
- Agents of S.H.I.E.L.D.: Bobbi and May have a conversation in Mandarin in the bank they plan to rob.
- There's usually a team per season on the American version of the The Amazing Race with a bilingual partner (most often Spanish) but no one has quite been able to hide behind a language barrier like a team in season 14. That season was filmed at the time of the Swine Flu outbreak and had to be rerouted at the last minute. They spent an unprecedented three legs in China because of it. Siblings Victor and Tammy used their ability to speak Mandarin to ask for favors and directions from the locals without having to talk to any of the other teams and without them being able to understand what the locals were telling the two of them. There was also a food ordering task that they were able to beat everyone else at by over two hours because they already knew how to speak the language. It allowed them to beat much physically stronger teams while there and eventually come in first.
- CSI: NY: When chasing a perp to Greece in "Grounds for Deception," Stella and Mac don't let on to the local officials that she knows Greek. She occasionally does the Bilingual Backfire thing to suspects in NY as well.
Patient: He says you're a very good doctor.
- One episode has a Chinese mother and daughter talk in Mandarin so House won't understand. Of course, he speaks it, making it a case of Bilingual Backfire.
- House blackmails a guy in Mandarin. Presumably, if he didn't get his money he'd repeat what he said in English.
- In another episode, Wilson is stitching up a Latino day-laborer who injured his thumb. House takes one look at the guy's red eyes, then tells him in Spanish to bring eyedrops the next time he decides to get high at work and accidentally breaks his thumb. Wilson, who doesn't speak Spanish, asks the patient what House said.
- In Frasier, Frasier and Niles have to speak French around Eddie the dog in order to not get him unnecessarily riled up over a potential walk.
- In Revenge, Emily offers to act as a translator when Daniel is having dinner with a Japanese investor. The "investor" is actually Emily's mentor, and the two of them spend the dinner talking about Emily's revenge plots while Emily makes up translations for Daniel.
- How I Met Your Mother:
- Ted and Barney befriend a Russian bouncer who takes them to an underground poker game. Ted ends up winning a lot of money from the other players who are very shady and dangerous looking. Just as it looks like Ted is going to get killed, the bouncer intercedes, shouts a few phrases in Russian and things quickly cool down. Ted and Barney are grateful to have made such a great friend but do not realize that he actually told the other players that he plans to rob Ted and Barney and will return everyone's money when he is done.
- When Barney first met Ted, he has Ted pretend to be his deaf brother to impress a girl. She starts signing at Ted (who signs back). Barney believes that Ted is playing him up to the girl, when he's really telling her that Barney's a liar, having her give him a fake number.
- Happens and also discussed in Northern Exposure. The older Native Americans all speak Tlingit when they don't want the youngsters to understand what they're saying. When Ed talks to Joel about this, Joel mentions a similar thing happening in Queens where Alter Kockers speak in Yiddish in order to keep secrets. Both Tlingit and Yiddish are dying languages; Ed decides to dub The Prisoner of Zenda into Tlingit in order to preserve the language.
- On the first episode of Fringe, a couple of Iranian businessmen speak Farsi to decide on a figure to pay Peter Bishop. Unbeknownst to them, he also speaks Farsi, and agrees to the figure they choose.
- In the Seinfeld episode "The Understudy", Elaine feels that her Korean manicurists make jokes about her when they speak to each other in Korean (she's right). Eventually, she brings along Frank Costanza with her, who speaks Korean, and gets upset when they insult him too.
- In NCIS, Gibbs and Abby often speak to each other in sign language to avoid other people hearing their conversation.
- On Impractical Jokers one time the mission was to get people to comment on bogus news stories in Times Square, and when approached two women commented "We don't speak English." It was lampshaded by the guy.
- Horatio Hornblower:
- In "The Even Chance", a French captain of a captured ship says to Hornblower that he swears he won't try to gain the command back again, and says his men won't interfere either. He in fact instructs them to wait until his signals them to take over the boat. Which doesn't work out great for them as Hornblower understands French himself and prepared for the situation. Reality Has No Subtitles and viewers who don't understand French don't know what was said.
- Hornblower and the Duchess openly discuss the Admiralty's super important dispatches which she's hiding. They are standing very close to a Spanish guard who's in hearing distance. Common soldiers probably didn't speak English, but Don Massaredo did and many a conversation was conducted in English. Luckily, he apparently didn't understand.
- On Orange Is the New Black, the Latina girls speak notably more Spanish in front of the white or black girls than they do when no one is around.
- On Narcos, the language barrier is used to keep mostly-monolingual Steve out of the loop on certain things. Colonel Carrillo also speaks English with Javi (a native Spanish speaker) in front of his men to prevent them from eavesdropping and passing information on to Escobar.
- The Bill. The detectives arrest an Eastern European drug dealer and force him to set up a drug buy. They insist he speak English while making the call so he won't pass on a warning, but when no-one shows up the dealer smugly points out that they never speak English while making a deal in case they're overheard, so his friends were warned anyway.
- In Jane the Virgin, Alba is in serious danger of being deported — despite being comatose and unable to speak for herself, leaving her daughter Xo scrambling to find a way to keep her in the country. While on the phone with Jane, Xo lets her know what's going on, but tells her in Spanish because there's a police officer (who doesn't know what's going on and would be obligated to report it if he did) in the room with her.
- In Heroes, HRG manages to block Matt Parkman's telepathy by thinking in Japanese (which HRG is fluent in).
- In Stargirl (2020) the supervillain Icicle's parents are fully supportive of their son's plan, and will sometimes speak Norwegian to discuss it in company. This backfires when someone gets suspicious and records them, and is able to translate it online.
- Lucky Dog 1 has many of the bilingual Italian-speaking characters switch to their native language when they're around monolingual English speakers and don't want to be overheard talking about the Mafia or gang-related affairs. However, one of the few instances where they seemingly forget to stop speaking English while discussing these confidential matters with one another inadvertently leads to an old woman overhearing, and realizing they're convicts on the run. This can lead to them being forced to silence her permanently.
- In World of Warcraft, completing the quests leading up to the Battle of the Wrathgate leads to this exchange. A bug, however, temporarily allowed players to understand the spoilered Draconic part, which alluded to events that were only explicitly revealed in the Fall of the Lich King patch.
Korialstrasz: My queen, do they know?
Alexstreasza: No, my beloved. [Draconic] They must not discover the fate of the young paladin. Not yet.
- The Legend of Zelda:
- The Legend of Zelda: The Wind Waker has the King of Red Lions talk to ancient beings in Old Hylian so Link doesn't realize he's the The Unchosen One. The game translates it in a New Game+.
- The Legend of Zelda: Breath of the Wild features a "Voe and You" class where Gerudo women are taught how to interact with men. When the teacher asks for the students' thoughts on how to respond to a guy who they are interested in, one student suggests initially pretending not to know the guy's language to inspire curiosity in him.
- In Stand Still, Stay Silent, five languages are spoken in the story world, so this happens often. At one point, Tuuri tells a train conductor in Swedish to pick up her cousin (who only speaks Finnish) and carry him into the train.
- In an early El Goonish Shive strip, Tedd and Grace have taken each other's forms for a date, and are trying (unsuccessfully) to hide this from Elliot and Sarah. When Tedd doesn't want Grace "taking a peek" in the restroom, he tells her to change back before going the bathroom, but he uses an alien language to do so.
- Paradigm Shift: A Triad gangster who got into a shoot-out with the police in the first chapter tries to stall for time while in hospital by refusing to speak anything but Cantonese to the officers guarding him. It works up until they bring in a detective who grew up in Hong Kong.
- Kevin & Kell: Frank (a lion) told Kell (a wolf) about his plans to overthrow R.L. in cat language (Kell have learned how to speak cat at this point), in order to prevent the word from spreading to R.L. Turned out R.L. knew how to speak cat as well, something he revealed to Kell when she visited him at the hospital.
- Not Always Right has many examples of customers covertly insulting the staff or discussing plans to shoplift or otherwise abuse the business by talking in a foreign language, only to be called out on it because the employee understands them perfectly. Their sister site, Not Always Working has similar examples with reversed roles.
- Subverted in The Boondocks, when kickball pro Huey is tricked by the rival Chinese team into deliberately performing poorly by telling him that if they lose they'll all be shipped to a prison camp. As they mock him in Mandarin for believing the lie, it is revealed that he's actually fluent in the language, and after dropping a slick retort in Mandarin to clue them in, he proceeds to effortlessly beat the crap out of them with the kickball.
- In World War II, the Japanese used former students who had studied in the US to listen in to American radio transmissions, so Navajo soldiers were used to speak their own language, completely baffling the Japanese. Canada did the same with Cree speakers.
- Many wives and mothers took especial delight in writing their Christmas lists or other secret things in shorthand, and then deliberately leaving it in plain sight for the husband and children to wonder.
- Often employed for playful teasing between friends or in romantic relationships. Yahoo Answers is full of questions like "my friend/gf said/wrote something she wouldn't translate, could you please translate it?"
- Natalie Portman did this with Hebrew in an Inside the Actors Studio issue, just to amuse herself. The Internet went nuts over this.
- Has been known to be Truth in Television, when both parents speak a language their child does not. Also with upper- and middle-class employers of lower-class servants. Thus in German and English the French phrase "pas devant les enfants" or "les domestiques" was semi-proverbial until ca. World War II, when French was still the foreign language most likely to have been learned in the "educated classes".
- Also Truth in Television when someone who is bilingual encounters someone they don't really wish to have a conversation with/they want to be left alone or the like. Some Japanese rock musicians do this in English-speaking locales since people expect them to not know English — giving them an easy out for encounters with non-Japanese-fluent fans or media. Pata of X Japan is famous for doing this — he has good enough English skills to work with English-speaking American artists and to pick up English-speaking groupies, but is also a Shrinking Violet and will happily pretend to be unable to speak English to avoid an encounter he doesn't want.
- In both world wars, Welsh regiments of the British Army spoke Welsh in clear on radio transmissions, knowing the likelihood of a Welsh speaker turning up on the German/enemy side was vanishingly small. (On one occasion when the 3rd Battalion Welsh Guards was fighting in the battle of Monte Cassino its positions were showered with leaflets in Urdu soon after its radio messages had been intercepted by Germans.) This idea was copied by the Americans, who used American Indians as signalers to similarly confound Japanese and German intercepts. Unfortunately for Welsh regiments in WW 2, Welsh was thought of by the Nazis as a dawn-language of the Aryan peoples, and a School of Celtic Studies had been set up at one German university. Once the Germans cottoned on, they had a certain number of Welsh speakers available to monitor radio transmissions... the practice was, however, maintained by Welsh units in the Far East. It is no longer used by the British army as so many countries have universities that teach Celtic languages. It did not go un-noticed that a fairly recent enemy, Argentina, actually has a Welsh-speaking minority population. And at least one university in Northern Ireland has a Celtic Studies department offering Welsh language as a module. For that reason, Welsh units serving in Ireland were strictly ordered to observe standard radio operating procedure and not to think of using the old trick, as it is just too well known.
- Similar to the above Welsh example was Irish during the early years of the Congo Crisis. Irish peacekeepers deployed in the 1960s would radio secure communications in Irish so as to provide an extra layer of security towards whoever was monitoring, whether Belgian, American or Congolese.
- Another example is Wenzhou dialect during a few wars in China. Wenzhou dialect is one of the most difficult dialects among the Chinese Languages, making it suitable to be used as a code.
- Herbert Hoover and his wife, Lou Henry, spoke fluent Mandarin and conversed in that language when they didn't want to be eavesdropped.
- Sports teams can employ this trope to keep their tactic a secret from the opposition. For example, South Africa has a whopping eleven official languages and English is generally used as the lingua franca. But when their sports teams play against English-speaking countries such as England, Australia or New Zealand, they sometimes use Afrikaans.
- Charlize Theron confesses that she and her mother like to speak in Afrikaans in public because it allows them to make snide remarks about people in their vicinity. This backfired once when the person they were talked about turned out to be an Afrikaaner.
- In World War II, the Germans began looting art from German-occupied France. Rose Valland, a French woman who was the overseer of the Jeu de Paume Museum, where the looted art was being stored, faked being unable to understand German. For four years, she secretly recorded where 20,000 French and Jewish art pieces were being sent.
- A cant, or cryptolect, is the jargon and slang of a group used to hide communication from people outside that group. Basically they create their own language barrier to hide behind. Various criminal subcultures around the world have used a thieves' cant to speak to each other without fear of being understood by victims or the authorities. See also: Cryptic Conversation.
- According to legend, a licensing deal between Saban and KISS fell through because, during a meeting with Gene Simmons, Haim Saban turned to his partner and said "And now we'll milk him dry" in Hebrew...to which Simmons responded "You idiot, I'm one of you" and walked out of the meeting.
- In some countries there are languages that are mandatory at school but are not commonly spoken at home, such as English for most of Europe, or a given country's second official language for a family that speaks only one of the official languages at home. Thus, those languages can be used by parents and older children to keep smaller children from understanding a conversation. Handy for planning surprises or just annoying your younger siblings.