Poirot Speak

On TV, many foreign people speak a weird mixture of English and their own language, often applying a ridiculous accent to both. As in, "Ich bin ein expert psychiatrist, especially skilled in ein field of phobias. Mmm, very well, mein Herr... please sit down while ich deal with your kleinem Problem." Interestingly, while they have no problems of saying tougher words like "skateboard" and "movie theater" in perfect English, they have to fall back on their native language for words such as "yes" and "no".

They also insert articles before most nouns. If the speaker is German, he will use "ein" (equivalent of "a") liberally, "der" (for "the") less liberally, and "die" or "das" (female and neuter equivalents of "the") rarely. Likewise, Spanish-speaking characters are more likely to use "el" rather than "la", and French-speaking characters almost always use "le". Russians, on the other hand, tend to drop the articles (since Russian has no exact equivalents of "a" or "the".)

This may be because the people who make TV shows assume that Viewers are Morons, and simple foreign words are the only ones the average viewer would recognize; alternately, it could be because they're the only words the writers know.

Not to mention that these characters sometimes impose their native tongue's sentence structure on English ("Please to be restful. It is only a few crazies who have from the crazy place outbroken."), mix up similar-sounding words without realizing it (such as dejected and ejected, for example), and generally mangle English idioms.

See also Gratuitous Foreign Language and As Long as It Sounds Foreign, wherein nobody's supposed to understand any of the words. Has some degree of Truth in Television, as slipping into your native tongue is rather common for those who are not completely fluent with a foreign language. However, the way this trope is often used in fiction tends to be the inverse of the way real people talk -- for example, a native English speaker in a Spanish-speaking country will (by necessity) tend to express the complicated stuff in English, and then (as a courtesy) throw in the handful of Spanish words he actually knows, which will tend to be stuff like "please", "yes", or "thank you": "Buenos dias, señor. Necessito un nuevo compression coil para mi hovercraft, por favor. Si, el compression coil. Gracias." It's sort of like saying "I actually bothered to learn some of your language, but unfortunately I can't talk about complicated things yet."

Anime & Manga
""Go down with StealthGao! Bon!""
 * Mio Hio in D.N.Angel mixes in English words with Japanese, both of which are accented.
 * Renais-Kardif Shishio from GaoGaiGar FINAL is French, and therefore peppers her speech with very basic French.


 * Swan White. Stallion White. Mic Sounders XIII.
 * All the German and French characters in the Hellsing manga (in the English translation). It's especially jarring when they're talking amongst themselves.
 * In Hana-Kimi, Oscar M. Himejima, whose native language is Japanese, tends to talk in German to be interesting, but the other (Japanese-speaking) characters respond like he's speaking Japanese anyway. Not as much Poirot-Speak as Gratuitous Foreign Language, but it seems to fit better here, nevertheless.

Comic Books

 * X-Men is fond of this, with its many, many foreign characters dropping in words of their own language all the time. As accents can be heard, this tends to be absent from adaptations (of course, the movies drop the accents for everyone but Nightcrawler... whose German is not convincing at all even to non-native speakers of German.)
 * Sometimes not even the foreign characters; Gambit the Cajun lapsed into something vaguely like French at the drop of a hat.
 * Well, some Cajun people speaks a dialect called "Cajun French", which is basically french words with english grammar (and outdated French words too, since it split from french a few centuries ago). It's no wonder than a cajun guy like Gambit ended here with this background, and is, for once, a totally Justified Trope
 * According to legend, Austrians who saw the movie would exclaim something like "Oh my god! We don't actually sound like that... Do we?"
 * The parody comic Twisted Toyfare Theatre likes to get a lot of laughs at the X-Men's expense by mocking this. The X-Men's gratuitous foreign words will usually have humorously inaccurate translations in footnotes; as an example, Nightcrawler's "Ja und splichist!" was translated as "I'm German."
 * The modern Vladek Spiegelman in Maus speaks in the "foreign grammar, English vocabulary" variant, making this Truth in Television unless the author, his son, was using artistic license.
 * In Strontium Dog, the presumably Norwegian Wulf uses der for the (though in Norwegian 'the' is a suffix to the noun, not a standalone word before it), and ja for yes. His sentence structure also varies between sensible and Yoda-like.
 * Hellboy comics include Johann Krauss, who is capable of explaining doctorate-level concepts in English. However, he routinely responds to questions with "Ja" or "Nein."
 * War comics, especially titles like Commando and Stock Parodies thereof, tend to ramp this Up to Eleven, especially for Those Wacky Nazis.
 * Marlene and Petite, the West German and French members of Jet Dream and her Stunt-Girl Counterspies, fit this trope.

Fanfic

 * A meta example: This trope is endemic among anime fanfic writers who have picked up a handful of basic Japanese words. Some writers will never deign to use English words like "Yes," "Thank you," or "Good morning," because you aren't an anime fan unless you know basic Japanese. This is particularly jarring when you do know basic Japanese, the author doesn't, and they try to use Japanese that they haven't learned yet.
 * In the chapters of Light and Dark The Adventures of Dark Yagami that take place in Paris, the characters use French pronouns, vaguely French verb constructions and occasionally French words while speaking (mostly) English.
 * Naruto fanfic writers love to use the word "teme" horribly wrong, based on a couple of lines in canon where Naruto says, "Sasuke, temee..." "Temee" is a hostile equivalent to the pronoun "you," though frequently fansubbed as "you bastard." Fanfic writers assume that it just means "bastard," and you see the nonsense phrase "the teme" or "that teme" all over fanfic. Also, it's not a (dis)honorific as in "Sasuke-teme," but you see that everywhere too.
 * The above goes for onore and kisama in many fandoms.
 * Also sometimes there Naruto-dobe
 * And they're convinced that Kit and Vixen are Japanese.
 * Hetalia has this in a lot of fanfiction. Most common examples are France, and Germany.
 * Replacing the "God" in sentences such as "Oh my God" with "Kami" is quite popular, and quite wrong: a lot of spirits that are nowhere near capital-G-God-tier, or even the lower tiers of Olympus, are called kami.
 * The Son of the Emperor is a bit of a peculiar example. While French and German words are mixed into dialogue written in English, this mostly done to convey the fact that the characters are speaking in those languages and not in English.

Film
"Karl: Mein name is Karl, ich bin Expert!"
 * A classic film example is Inspector Clouseau from the Pink Panther movies, expertly played by Peter Sellers. Subversion: Clouseau's horrendous (and fake) French accent was so thick the French characters in the movies had moments where they could not understand him.
 * Several of the jokes are actually based on people expecting him to speak like this: for example, he says English room like the French rhume (cold (the virus))...
 * The whispering among the Frenchmen in Monty Python and The Holy Grail is full of this. When they are about to Drop the Cow, the order is whispered in Franglais: "Fetchez la vache!". Later when they bring in the Trojan Rabbit, they cannot understand each other in French and have to switch to English: "C'est un lapin, lapin de bois. Quoi? Un cadeau. What? A present. Oh, un cadeau."
 * In Inglourious Basterds, recognizable words in the French and German dialogue are occasionally reproduced untranslated in the subtitles, producing a Poirot-Speak-like effect even though the characters are speaking entirely in their own languages.
 * It actually comes off more like Gratuitous German, since it's mostly just words like "wunderbar," "mein Fuehrer," "ja," or "nein."
 * Borat.
 * A minor German character in The Big Lebowski speaks like this when starring in a porno.

"Janet: "You need to speak English or French. Frenglish is not a language.""
 * Inverted in The Terminal. When Viktor Navorski is beginning to grasp the English language, he usually uses English words for basic pronouns, prepositions, etc., but falls back to Krakhozhian when referring to more specific things - like mustard.
 * Dominique from D.E.B.S.

Literature
""Did I tellez vous about le chemise je trouvez at le Bendel's? C'est tres froid. Mais je ne affordez pas it at all so je chargez a Mama. Now she'll be pissoired a la maximum. Have to frapper les libres now--examination terminal de la français is demain...""
 * Named for Detective Hercule Poirot, who spoke this way as part of his Funny Foreigner facade. Hercule speaks fine English at the end as he explains step-by-step how he solved the case. Other characters have commented on it.
 * Poirot's speech is something of a subversion, as he uses his accent to disarm suspects, making them think he's only a Funny Foreigner when it's really "just an act".
 * Another notable literary example is Professor Van Helsing of the novel Dracula; his style of Poirot Speak is more the "Dutch grammar, English vocabulary" type.
 * There are a trilogy of books by Miles Kington, entitled "Let's Parler Franglais", "Let's Parler Franglais Again" and "Lets Parler Franglais Une More Temps", which teach a mangled version of French of this type (for comedy but presented as serious language lessons). Franglais is described as "The language you can speak if you know English and O-Level (Middle School) French".
 * P. J. O'Rourke's "Fake French in Nine (Neuf) Easy Lessons" is another instructional text on Franglais.

""For you, Britischer pig, ze var is over.""
 * There is also a series of books full of the mistakes Dutch people have made whilst trying to speak English, but while still using Dutch words/grammar. This stems from the fact that English and Dutch are related, and share many of the same words. Sometimes words sound familiar, but mean something slightly different, but hilarious, or something different entirely.
 * It also comments on the fact that a lot of Dutch people literally translate Dutch proverbs into English.
 * Herald Alberich from Mercedes Lackey's Heralds of Valdemar series routinely speaks Valdemaran with Karsite word order. He was born and raised in Karse and only ended up in Valdemar after being kidnapped/rescued by a Companion, who eventually psychically fed Valdemarian vocabulary into his head... and only vocabulary, leading Alberich to use Valdemarian words with Karsite grammar.
 * Used by Fitz Kreiner, from the Doctor Who Expanded Universe, who cannot communicate in German but is simply being weird:


 * Used in The Da Vinci Code frequently. The second line of dialogue after the prologue reads, "Mais monsieur, your guest is an important man." This is representative of most conversations involving non-native English speakers in the book.
 * Harry Turtledove uses the same tactic to make sure you don't forget that people with French names in obviously French-speaking places speak French, or whatever other lingual group the story focuses on. In the Worldwar series, very little of The Race's language is ever translated into English in the text, but they have distinctive speech patterns which are often indicated (such as the 'interrogative cough'), which people will often use even when speaking human languages which have their own auditory cues to indicate that a question is being asked.
 * In the novel version of '2010 (which portrays rather friendlier Soviet-American relations than the film), the "Russlish" spoken aboard the craft is something of a running joke among the crew of the Leonov, with "STAMP OUT RUSSLISH" posters being mentioned at one point. The American viewpoint character, Heywood Floyd, even mentions speaking to another American (Walter Curnow) in Russian at one point. This is, as noted below, Truth in Television: mixtures of Russian and English have proven to become remarkably common in space, where Russian cosmonauts and American astronauts frequently spend months together (first aboard Mir, and now on the ISS), although when the book came out (1982) only one US-USSR joint project (1975's Apollo-Soyuz Test Project, which lasted all of 44 hours) had ever been tried.
 * in Eric Flint's 163X series (started with the book 1632, written by Flint alone, now includes almost 20 print books, most co-written by Flint and another author(s), many that are anthologies of short stories by many authors, and, of course, the online 'zine "Grantville Gazette", which is formalized, canonized fanfiction), the fictional West Virginian town of Grantville, in the year 2000, is picked up and dropped in the middle of the 30 Years War (in 1631) in the middle of the Germanies. A patois (or pidgin, depending) quickly develops, called "Ami Deutsch" – "American Deutsch" or "American German". So you have a huge cast of characters who do this so habitually, many readers start doing it in *real life*.
 * The Hungarian Toby Esterhase from The Quest for Karla trilogy, who manages to do this in multiple languages.

Live Action TV

 * Mad TV has a recurring sketch of well-known American TV shows "dubbed" into Spanish; they use English sentence structure, and words that the average American wouldn't recognize are simply said in English. ("Pero Jack, si Sr. Roper sabe que tu eres heterosexual, él va a evict-te.")
 * "No soy un meathead!"
 * The History Channel once aired a program about Martin Luther, and they had a voice actor reading a passage of English text in the character of Luther – he adopted a German accent and replaced "and" with "und". This patronizing behavior ranks about equal with the Discovery Channel shows that depict sound in space.
 * Herr Lipp manages to mangle virtually every sentence he speaks in such a way that it becomes a Double Entendre... made especially funny in that you can never quite tell if he's doing it on purpose or not. "If you don't understand any of my sayings, come to me in private and I shall take you in my German mouth. Alles klar?"
 * Pretty much every character in Allo Allo and one of the major plot points and sources of humor in the show.
 * Omar's boyfriend Renaldo on The Wire does this with Spanish.

Music

 * Not quite an example, but "Weird Al" Yankovic's song "Taco Grande" is mostly in English with some whole sentences in very simple Spanish. Anyone who took even a year of Spanish should be able to figure out what they mean. This doesn't include the lengthy Spanish monologue, which was written in English and translated by a bilingual Scotti Bros. Records employee.

Professional Wrestling

 * Done pretty often in Professional Wrestling, more recently with Santino Marella.
 * Every single Hispanic wrestler in WWE does this.

Stand-up Comedy

 * Peter Serafinowicz (got it in one) lampooned this by having Poirot say that he doesn't actually know French, he just uses enough French words to convince people he does.
 * Many of the French phrases in Dave Barry's writing are American idioms or brand names clumsily forced into French grammatical structures, such as "La Ware de la Tupper" or "Que l'enfer, c'est seulement Canada" ("What the hell, it's only Canada"). Some are just As Long as It Sounds Foreign sentences relying on Inherently Funny Words.
 * Anna Russell's routine "Schreechenrauf," introduced as a pastiche of Wagnerian arias for dramatic soprano, is actually a parody of the Ring cycle, with mangled Anglo-German phrases like "wir fallen in lieber" set to Richard Wagner's music. The aria reaches a climax when it puts down one of the characters from Götterdämmerung (Gutrune, daughter of Gibich) as "Gutrune, die Götterdämmerung Gibich!"
 * She does the same thing with what can only be described as dog-Italian, in "Canto Dolcemente Pipo", from the opera La Cantatrice Squelante.
 * Comedian Eddie Izzard's bit on Martin Luther spirals into an exploration of this trope: "Then Martin Luther said 'hang on a minute!' Only in German, so, 'ein minuten bitte... ich habe einen kleinen problemm ... avec dieser, uhh, religione.' ...He was from everywhere."
 * Izzard also does a bit on attempting to communicate in France with schoolboy French, most of which involves dragging a cat, a table, and a monkey everywhere so that his vocabulary stays applicable. This is sort of complicated/averted because Izzard can actually speak pretty good French – good enough to do whole shows in the language.
 * Czech humorous singer Ivan Mladek once did a routine where he spoke German, slipping back into Czech. He told of a television show, approximately "Look Out For The Curve", and translated it as "Achtung! Die Kurve!" (Which, to Czechs, sounds like "Look out! A whore!" as kurva means prostitute...)

Theatre
"Cadets (entering): Mille dious! Capdedious! Pocapdedious!
 * Used in West Side Story. The Puerto Ricans speak English among themselves, punctuated with "por favor" and "una poca poca?" And "si" is near-ubiquitous.
 * Anyone Can Whistle has the scene where Fay puts on a wig, dress and accent (ze accent being ze most outrageous) to disguise herself as a sexy French lady, and solicits "Docteur" Hapgood to accompany her in the duet "Come Play Wiz Me."
 * That's kind of the joke. As the Docteur sees right through her preposterous disguise, but decides to play along anyway.
 * Bill Wyman's single Je Suis Un Rock Star.
 * Cyrano De Bergerac: Lampshaded by Ragueneau at Act II Scene VII, who hears only a few words spoken in Gascon dialect to realize that The Cadets are a regiment composed of Gascons… and to be fearful of them (they have a reputation). Notice those are the only Gascon words in the play (apart from some in Act IV), because the Gascon Cadets all talk in SurprisinglyGoodFrench:

Ragueneau (drawing back startled): Gentlemen, are you all from Gascony?

Cadets All!"

Video Games

 * All of the Wolfeinstein sequels embody this trope to an ear-torturing extent. The original Wolfenstein 3D actually featured Nazis speaking German. The sequels are a mix of horribly accented English with a few simple German words throw in like jawohl, achtung, etc.
 * The original 1981 Castle Wolfenstein game notably had the Nazis speaking correct German as well (the C64 manual included a short phrasebook so the player could understand what was being said). At the time digitized voice was quite uncommon in a computer game, and even Wolfenstein 3D predated the importing of cinematic values into video games, making this something of an Unbuilt Trope.
 * Manny Calavera from Grim Fandango does this, along with a few other characters.
 * Several characters from the Ace Attorney series, most specifically Jean Armstrong (French words), Olga Orly (Russian sentence structure), and Klavier Gavin (German words, usually "Herr" and "Fräulein"). The latter is particularly strange as his brother, Kristoph Gavin, speaks such meticulous and perfectly articulated English that one is almost tempted to read a slight British accent into his dialogue.
 * It should be noted that at least one and possibly all three of those are not the nationality they appear to be.
 * Chrono Cross does this constantly, and most conspicuously with Pierre and Harle, the two characters with faux French accents. They even ludicrously use the word moi for both 'I' and 'me'. This is because the text was actually in standard English, run through an "accent generator" that replaced particular words or word beginnings/endings with others. This allowed the localization team to just translate one line and alter it, rather than translating 44 of them.
 * The Russian voices from Command and Conquer: Red Alert 2 had this, with "da" being the most common untranslated word. They mostly got right the Russian habit of missing out "the", however (Russian has no articles).
 * Jeanne D Arc has Colet, who speaks in a terribly stereotypical French accent. In a game where everyone is already French.
 * Secundo from Beyond Good and Evil liberally sprinkles his speech with Spanish words (confusingly, a couple of Italian and French ones, too [the latter presumedly untranslated from the original – "et voilà!").
 * In the original French, it's a combination of Italian, Spanish and English.
 * As the current page image shows, Team Fortress 2. The Medic, the Heavy, and The Spy all speak mostly fluent English, but will revert to their native (?) languages for things like "Yes", "Thank you", and the occasional Foreign Cuss Word.
 * As the developers mentioned, this is a part of Stylistic Suck.
 * The Heavy does this in Poker Night At the Inventory by Telltale Games. His banter constantly sounds faux-Russian (something like "You have job, yes?").
 * Mercenaries 2 replaced enemies that spoke their native language with English-speakers wielding thick accents. They seemed to know how to say 'explosive' in Spanish... and that was it.
 * Resident Evil 4 does this with everyone who's not a normal villager. Normal villagers will speak only Spanish (though sometimes what they say doesn't make much sense, due to not-so-good translation), but every other native will sometimes slip into a "Señor", for instance, despite being perfectly able to discuss genetic manipulation science in perfect English.
 * Halo: Reach has this with some of the Hungarian-speaking civilians.
 * Zig-zagged for Russian characters in the Call of Duty series. In the World War II-based titles, they regularly speak accented English for the sake of the player being able to understand them (which is clearly Translation Convention, as one of the final journal entries in the original game has the Russian player character say he could not understand what an American soldier he met with was saying), with the occasional swear in actual Russian thrown in when necessary. In the Modern Warfare sub-series and Call of Duty Black Ops, however, they regularly speak Russian, only saying things in English when the player needs to know what they're saying.
 * In The Elder Scrolls V Skyrim, the dragons tend to interchange their own language with those of mortals frequently. Aldiuin does this regularly, and Odahviing's mortal language is more stilted. Paarthurnax also does this, but as he's spent thousands of years conversing with mortals, his command of the mortal tongue is far better, and he's friendly and polite enough that when he slips into his natural tongue, he's quick to translate (unless it is a word he knows you understand, like "dovah"). Dragons are also noted as beings for whom language is an intrinsic part of their existence, so them switching between languages without thinking about it is not a conscious decision.

Webcomics
"Anja: Is so sad. All those figures standing there. Like they waiting for something."
 * Lampshaded in The Adventures of Dr. McNinja, in which a group of Mexicans who speak Poirot Speak are redundantly subtitled. "Hola, señor" has an asterisk placed next to it, and the footnote at the bottom of the page helpfully translates it as "Hello, mister"; the word "policia" is spoken four times in a single speech (it is, in fact, the only Spanish word on the page), and the comic dutifully provides four footnotes reading "police."
 * Anja Donlan from Gunnerkrigg Court is not a native English speaker. This is shown in one Flash Back, where she makes several grammar mistakes. (By the present day, over a decade later, her English is pretty much perfect.)


 * The nazis in Irregular Webcomic.
 * In Darths and Droids, Count Dooku is apparently Space French, so he uses lots of Space French words in his speech. By Translation Convention, Space French sounds exactly like French.
 * DiDi from Ménage à 3 switches regularly between French and English. Unlike most examples, her French is not necessarily words that most English speakers would already know, and they aren't subtitled, so it takes context clues to figure it out if none of the other characters say anything that translates it. Theoretically, reading this comic should improve your knowledge of French.
 * Elf Blood's Carlita Delacroix is the most Egregious offender of this. Interestingly, although she had a Cuban mother and a French father, she only ever talks with a French accent.
 * Hell, it might even be completely put on seeing as she went to school with the others and they don't have any kind of accent whatsoever.
 * The Sages, being remnants of the original Alfen civilisation, will occasionally pepper their speech with Germanisms.
 * The Remix Comic version of Jet Dream exaggerates the trope to ridiculous levels. Marlene and Petite are even worse than their original comic book counterparts, and any minor character from another country is guaranteed to have an utterly ridiculous accent and speech pattern.

Web Original

 * In this Let's Play of X-COM: UFO Defence, a fan entry in Chapter 3 uses this. "I vaz issued mein waffen today. It is ein stick."
 * Zer Germans of AH Dot Com the Series use a combination of this an Funetik Aksent. Lampshaded, as this is said to be a side effect of the Stereotypica Virus that ravaged their world.
 * Yu-Gi-Oh the Abridged Series has the Kaiba Corps Nazi's, Kaiba's two lackeys who speak like this. When Kaiba asks them to tone it down they hastily agree "Yes mein führer."

Western Animation
"Raimundo: What Omi just did to that last sentence is what we're going to do to you!"
 * Almost every foreigner in the Looney Tunes series, especially in the Pepe LePew cartoons (in which Poirot Speak even appears on signs).
 * All of the foreign Superfriends added to be minorities: Samurai, Apache Chief, and El Dorado.
 * They were really insulting, by the way.
 * Seanbaby goes into humorous detail about just how stupid this was on his webpage.
 * Road Rovers: Exile, the Russian, frequently peppered his speech by putting "-ski" at the end of random words.
 * Xiaolin Showdown: Omi, one of the main characters, demonstrates this trope repeatedly in most episodes by butchering even common figures of speech. He is always promptly corrected, except in one case: none of the other characters could seem to make heads or tails of his words enough to even guess at what he meant.

"The Inspector: "Don't say sí. Say oui."
 * At least one mangling that none of the others could figure out was, "This is not a delicacy!" after facing resistance trying to boss around the team. Mangled word being democracy, natch.
 * Teen Titans: The animated series, at least, uses this for Starfire in the stilted but understandable version. She also adds particles (usually "the") before the names of villains ("the Cinderblock" or "the Mumbo"), and is also an example of Pardon My Klingon with her use of untranslatable Tamaranian words in numerous contexts.
 * The fact that Starfire does this is even more vexing, considering her entire understanding of the English language stems from a direct psychic download from a native speaker, meaning she should have instant and near-perfect understanding of the language. The only words from her own language she should be using are ones without direct translations.
 * Just because she understands it doesn't mean she's used to speaking it.
 * In The Inspector cartoons from DePatie-Freleng Enterprises, The Inspector (an Expy for Inspector Clouseau) has a fairly mild accent, though he does pepper his dialog with "oui" and other short words. In the early cartoons, however, his Sidekick, Sgt. Deux-Deux, speaks with a mild Spanish accent -- and, as a Running Gag, often says "sí", to the Inspector's irritation. This was phased out in later cartoons, possibly due to Political Correctness.

Deux-Deux: "Sí, Inspector.""


 * On at least one occasion, si was the correct thing to say even in French (positive reply to a negative question).
 * Played for Laughs in the Family Guy episode "The Road to Germany", when a Nazi guard describes the fleeing Brian, Stewie, and Mort as "Ein dog, ein baby, und ein Art Garfunkel".
 * In the multi-ethnic team of Captain Planet and the Planeteers, only Linka occasionally spouted Russian exclamations. How she (or any of the others on the team) learned English in the first place is left unexplained.
 * Toki and Swkisgaar from Metalocalypse, more so in fanfictions and when thanks to the internet, when one can look up common Swedish and Norwegian words and phrases.
 * Antoine from Sonic the Hedgehog (SatAM) painfully mixes English and French in his sentences and his accent makes certain words impossible to interpret, much to the confusion of the other characters.
 * Sal from Futurama pluralizes nine out of every ten words that come out of his mouth - even those that were already in the plural in the first place.

Real Life

 * This is generally not all that uncommon for the average speaker of foreign language. Certain common standard words are so ingrained in your speech patterns that it can be hard to drop them without conscious effort when using them in casual speech, ranging from words like "thanks" or "bye" to swearing. Generally the more surprised you are, the more likely you are to respond in your native tongue regardless of the surroundings. The most obvious example is probably when a startle causes you swear: it is nearly impossible not to slip into your native language when doing it and, conversely, swearing in a different language requires a conscious effort for which you don't have time when startled.
 * Unless you learned swearing mostly from movies, music, the internet and other kinds of anglophone cultural export. Also, teens absorb this kind of English language pop culture right when they start rebelling against their parents' "no swearing" policies, and the parents often won't understand a hissed "Shit!", so you get away with it more easily. Words like "fuck" and "shit" and pretty much all kinds of sexual terms seem much less offensive than the equivalent words in languages like German or Japanese. Some media actually uses this as a form of Getting Crap Past the Radar. In Panty and Stocking With Garterbelt, for example, almost all swears spoken are in English rather than Japanese - the censors didn't mind, but the intended audience would know what they meant.
 * This is essentially the origins of "pidgins" -- crude languages formed by haphazardly combining words and grammatical structures from multiple languages. Typically developed as a "make do" language between groups who do not share a common language or language family, and who maintain a significant geographical or cultural distance, typically for the purpose of enabling trade between them.
 * Many of these pidgins eventually become fully fledged creole languages later on, combining many aspects of the languages they were derived from.
 * In Michael Palin's New Europe, the people who are showing him around do miss out words when speaking English to him and one did use the Romanian word for "yes" rather than the English one.
 * The famous "blinkenlights" warning sign.
 * Often justified in real life. Children raised by parents who primarily speak one language in a place where most people speak another will often grow up speaking to their parents in unusual combinations of both. Typically, verbs, pronouns and grammatic structure will remain in the parents' native tongue, while nouns and and adjectives will shift far more quickly to the new language. The result is something almost identical to Poirot Speak. In some cases, it can be how pidgin languages, like Bungee or Chiac in Canada, are formed.
 * Franco-Manitobans (and other fully fluently bilingual people) do this, leading those of us who have to switch brain-language gears before changing languages completely in the dust.
 * Jean-Claude Van Damme is particularly known for that in France when he kept using English words in the middle of his French sentences like his infamous "aware". The fact that his "philosophical" sentences are as clear as someone being high and drunk at the same time doesn't help either to understand him, no matter the language used.
 * In areas where two languages come in close contact, languages will often become mingled in a phenomenon called codeswitching. In the United States this is particularly well known in the case of Spanglish, which is widely spoken along the US-Mexican borders as well as in areas where English and Spanish speakers mingle frequently (especially restaurant kitchens). It's very similar to, though a bit less stable than, the formation of pidgin languages. (On the International Space Station, it's not that uncommon for the astronauts and cosmonauts to speak in a mixture of English and Russian.)
 * Quite true in Malaysia/Singapore to the extent that a person claiming to speak Malaysian or Singaporean "English" should have a good working knowledge of English, Malay, and several Chinese dialects, including Cantonese and Hokkien, as English speakers will use whatever relevant word they can think of in the other languages in the right English grammatical place. Also, since this is more of an unofficial language, speakers can switch from "barely understandable to anybody who isn't a native" to "somewhat professional, easily understandable to most English speakers".
 * Due to the popularity of India-based outsourcing, this is quite common in the IT industry; particularly the US and Great Britain. Typically it's an English vocabulary combined with Hindi grammar and idiomatic usage. The degree to which the trope applies depends on how fluent the speaker is in English. On the extreme non-fluent end, it ofen ends up with a collection of English words arranged in an almost incomprehensible (to a non-Hindi speaker) structure.
 * Common in the sciences, at least in the United States. Many scientific terms and nomenclature were developed by English-speaking researchers; however, international students and post-docs are gaining greater representation in American universities. Since many of these students received primary and/or undergraduate education in English, it's not uncommon to overhear conversations in Hindi interspersed with words like "DNA" or "plasmid."
 * Justified in that it's common to derive scientific terms from the "sciencey" languages (Latin, Greek and English).
 * And sometimes justified in that there is no official translation from the German/Latin/Greek/English word, or, alternatively, that the official translation is to leave it as it is. That applies to more than science, of course.
 * In Spanish, there is a false friend of this trope where the scientific term is indeed translated, then abbreviated through Spanish grammar to sound just like Poirot speak. ADN is DNA, for example, from ácido desoxirribonucleico, from deoxyribonucleic acid.
 * It has more to do with convenience, similar to bilingual case, then undergraduate education. For example in conversation in Polish I can drop words like "coursework" etc. Usually it is aversion of Poirot Speak as the words borrowed tend to be connected with specialisation - not generic ones.
 * This is common in other countries as well, thanks to almost all international publication and communication in the sciences being in English. For example, while there are German terms for some bioscience terms (and you could legitimately invent translations for the rest), they aren't really in use anymore. These days, it's less work writing your Bachelor's thesis entirely in English than try and translate all the technical terms into unwieldy German for your pedantic professor. You're going to have to learn it anyway, if you ever want to publish anything, so why not start early? They've even started introducing Master courses that are conducted entirely in English, to prepare the students and because it's just easier to stick to one language.
 * This is also common in countries where a particular subject is taught in a language not native to the country. For instance, medicine in most Arab countries outside Syria and Algeria is taught in either French or English, depending on what other country has colonial or other historic ties. As a result, you get Egyptian and Jordanian doctors speaking Arabic with English words like "blood pressure" and "intravenous" and "lung cancer" showing up...which makes it difficult to talk to a Lebanese doctor, who will know them as "pression artérielle", "intraveineuse" and "cancer du poumon", and both would confuse the hell out of the Syrian doctor, who knows only "daght ad-damm", "qastara wardiyyah", and "saratan al-ri'ah". All, mind you, while speaking Arabic.
 * Graffiti seen on Spanish sign in bus: "No sneako into USA, OK?"
 * It is extremely common for Muslims of any language and ethnicity to pepper their own native tongue with literally hundreds or thousands of different bits of Arabic religious parlance, to the point where many sentences of theirs could hardly be said to be in any other language at all. Naturally this, along with many Muslims being unable to make out the difference between being Muslim and Arab, creates endless confusion and frustration for those of us in the faith (sorry, "ummah") who don't know much Arabic.
 * It probably works this way for most religions: walk into a Jewish kindergarten class, sit back, and don't have a clue. But on the bright side, the Shabbos Ima and Shabbos Abba will most likely share some nosh with you, because Morah taught them about v'ahavta l'reyacha kamocha, and they want to practice the mitzvah.
 * This is also the case in places in Southeast Asia who are making strong attempts to intigrate English into their schools and workplaces. The result is "Konglish" (Korean/English), "Japanglish" (Kapanese/English) or "Chinglish" (Chinese/English).
 * Sometimes, when two people who know only a little bit of the other person's language are talking together (say, English and German), then if the english-speaker knows enough german to basically package the english in a german format, it makes comprehension much easier.
 * The English Premier League attracts a lot of foreign players and it is interesting to contrast those who learn English and then move, with those who move then learn English. The former usually do speaking English with an accent - either their native or American, while the latter often acquire some of the dialect local to the club they play for. A particular treat is a player who was exposed to some English at home but hasn't yet taken formal lessons and is picking up stuff from team mates and listening to the crowd. It incorporates this trope for their general utterances mingled with odd phrases in a broad local accent when talk turns to actually describing the football.