During a party in Amadeus, Mozart does some humorous impressions. When Salieri (in disguise) asks, "Do Salieri", Mozart launches into a snorting, gibberish-laden parody while playing "Twinkle Twinkle Little Star" that ends with a truly epic fart. Of course, it's not played so much for humour as for the sake of reinforcing Salieri's animosity towards Mozart. And given what we know about the Real Life Mozart (see the Music section), it seems he really did enjoy that kind of humour.
There are two kinds of jokes in the Austin Powers movies. If it's not making fun of the spy genre, it's this.
Each of the Back to the Future movies had at least one scene where one or more villains ended up covered in manure. It was kind of a Running Gag.
The epic campfire scene in Blazing Saddles features a crew of cowboys eating beans and delivering a storm of farts and belches. The scene was actually considered edgy in its day. It's rather surreally subverted by the early television broadcasts of the film though, as the sound effects for that scene were removed by the censors, leaving a two-minute sequence of cowboys sat round campfires eating and periodically standing up then sitting again, while the fires flare slightly. Later versions had horses whinnying when they stood up, which was even more surreal.
In the original film, Charisse wants to go the bathroom, but her father Dr. Dolittle stops her because there are ducks in a goat in the bathroom. He tells her that she's drinking too many liquids and needs to go back to bed, but she insists she has to go. He manages to hide the ducks in the bathroom and somehow manages to get off without her seeing any of what is going on, even though the house is filled with animals.
In the same film, Maya sneaks her guinea pig Rodney into the hospital during the big meeting with Calnet where the merger is supposed to be signed. He sneaks off into a bathroom and ends up sniffing around the rim of a toilet, only for a woman that Dr. Dolittle treated earlier in the film for a shellfish allergy to come in and sit down, trying to sneak another snack. She sits down on him and realizing this and hearing his squeaks, they scream at each other. She flushes the toilet and leaves, and he shouts "Somebody get the license plate number! I have just been violated!"
Drop Dead Fred includes a scene where he tracks dog poop on the carpet with his shoes.
Dumb And Dumberer has a scene with Harry accidentally smearing melted chocolate all over a bathroom, which then is of course mistaken for something else.
It also turns it Up to Eleven with the whole scene involving making use of a broken toilet...
Epic Movie is absolutely full of toilet humor related to farts, burps, vomit, etc.
There is a scene parodying Harry Potter which has an old, ugly, and pregnant Hermione farting a lot.
The scene where Susan chugs an entire keg of beer obviously ended with this. She pukes a ton of vomit at two guys, says she's fine, proceeds to puke over two more guys, and finally, obviously still needing to puke, she locks lips with a Legolas look alike and starts to puke down his throat as he struggles to break free. This is considered so gross that all of their allies don't show up for the final battle.
According to Hop, jelly beans are actually the excrement of the Easter Bunny.
Hotel for Dogs: The dogs poop and pee on the floor, so they get given special dog toilets, which the villains fall into.
Idiocracy: "And the number one movie in America was Ass", and that's all it was for ninety minutes, a farting ass.
In Iron Man 2, a drunken Tony Stark amuses the guests at his party by demonstrating the correct way to relieve oneself in the Iron Man suit. This does not involve removing or opening any part of the suit.
The Italian Christmas comedies are made of this. You might wonder why they keep making them.
While not constant, the giants from Jack the Giant Slayer do fart, belch and pick their noses, forgivable because they are portrayed as being grotesque creatures.
The Jerk: Navin's dad tries to teach him the ways of the world - he points to a pile of cow crap and tells him "This is shit." then holds up a tin of shoe polish and says "This is Shinola." Navin distinguishes one from the other...then walks through the one on the ground.
Kenny is an Australian Mockumentary film about Kenny Smyth, a Melbourne plumber who works for corporate bathroom rental company Splashdown. A lot of the film's humour derives from the septic emergencies has to deal with supplying port-a-loos to events.
Looney Tunes: Back in Action contains a scene where Taz makes his entrance doing his usually gibbering which he usually ends with blowing a raspberry but farts instead.
One of the other members of the He-Man Womun Haters Club's attempts to sabotage Alfalfa's date with Darla is with a cat litter sandwich.
Buckwheat: Don't worry, it's pretty fresh.
In the scene where the clubhouse catches fire, Petey's attempt to put out the fire is by peeing on it.
When Alfalfa is put on probation for burning down the clubhouse, he is forced to guard its remains. After a Nightmare Sequence that takes place on a rainy night, Alfalfa asks his friends why he's soaking wet (it was due to a hole in the tent), and Porky tells him that he used to have the same problem.
This exchange when Buckwheat and Porky tell Alfalfa why he can't see Darla:
Buckwheat: Number one, she's not at home because she's at a ballet recital. Number two... what was number two? (Porky whispers something in Buckwheat's ear.) Buckwheat: Not that! The other number two!
The movie Música de Viento (Wind Music, or sorta), a Mexican movie starring Roberto Gómez Bolaños (a.k.a Chespirito), about a man with Hoplophobia (fear of gunfires), who made him fart loudly each time he sees one. The joke of the movie it's the protagonist trying to do anything to disguise the noise, for example, open a bottle in the same time he fart.
In the first movie, the children make up rude names: "Oglington Fartworthy", "Booger McHorsefanny", "Knickers O'Muffin", "Sandra", "Bosoms", "Bum", and "Poop Bum".
The second movie has Cyril joking that the farm is the "Land of Poo".
Our Friend Power 5: While being punished for almost getting Hyuk killed, Dalgeun really has to go to the bathroom, to which his boss allows. Dalgeun staggers out of the room, looking sick and farting loudly.
No Holds Barred: During an exhibition fight where Zeus is competing, two of the main villain's stooges stop in the restroom, which is very poorly maintained, to say the least. (The overflowing toilets are full of excrement.) Eventually, a tough guy comes and makes fun of the small endowments of the stooges. Also, there's this "delightful" exchange:
In Paddington, the titular bear gets his head stuck in the toilet when learning about bathrooms.
In The Party, Bakshi (Peter Sellers) has to take a leak, but can't find an unoccupied bathroom. Getting increasingly desperate, he starts to cross a room when the girl he's sweet on starts singing for a crowd - he stops out of politeness and writhes in smiling agony for the duration. After he finally relieves himself in the master bathroom the toilet won't stop running, and in his attempt to fix it, he breaks the tank lid on the floor, drops a watercolor painting into the tank, and floods the room.
Peter Rabbit has a joke about sticking a carrot up someone's butt and a joke about checking to see if the toilets are clean by drinking from them.
There's quite a bit in Scary Movie, possibly to the point of overuse.
Thunderpants, a film about a kid who farts a lot. It's basically fart and toilet jokes all the way through.
In a very unlikely place to find this trope, 2001: A Space Odyssey has a scene where Floyd is reading a long, detailed list of instructions on how to use the Zero Gravity Toilet. Part of the reason why this works is because it's actually Truth in Television. Real-life Zero Gravity toilets are insanely complex and require a ton of training to use properly. A casual passenger would require such a set of instructions.