South Park: Bigger, Longer, & Uncut is the first and only South Park feature film to date (unless one were to count the Imaginationland trilogy, which is subject to debate). It was released in the United States and Canada on June 30, 1999, and received positive reviews, stating it's "brilliant in its own twisted way." Though it amassed $85 million in box office, this is commendable considering that it is the highest grossing animated movie to be rated "R". The film, a musical containing memorable songs, was nominated for an Academy Award for Best Song for "Blame Canada". The film contains many underlying messages, including censorship lessons, and that you should accept what is your fault, and not try to blame it on someone else.
The film opens with the innocent-looking Stan, Kyle, Kenny, Cartman and Kyle's adopted Canadian brother Ike going to see the CanadianTerrance and Phillip movie Asses of Fire ("Mountain Town"). Although they have enough money to buy their tickets, they arrive at the theater to find they are forbidden to go see the movie. Due to consisting almost entirely of crude jokes, constant flatulence humor, and excessively strong language, the film is rated R and the boys must have a guardian with them. Wanting to see the movie, the boys hire a homeless man to buy tickets for them. This plot is a success. By the end of the film, though, everyone except for the boys has walked out, considering the movie to be far too vulgar ("Uncle Fucka"). Later, at Stark's Pond, the boys impress their classmates by imitating the movie's strong language, causing all the children to want to see the movie as well. Afterward, Wendy skates over to Stan and introduces Gregory of Yardale who Stan thinks Wendy is in love with ("Wendy's Song").
By the next day at school, the whole class, save for Wendy and Gregory, has seen the movie. Cartman, Kyle, Stan, and Kenny get sent to the school counselor, Mr. Mackey, after repeating the word "fuck" and other obscenities to Mr. Garrison. In the counselor's office, Mr. Mackey tells the boys that he has notified their mothers of the incident, and tries to find out where the language originated from. The boys' mothers arrive and Cartman reveals that they heard them in Asses of Fire, which inadvertently makes the somewhat radical Sheila angry. Later in the cafeteria, Chef tells Stan (or rather, lets it slip) that to get girls to like him, he must find the clitoris, which Stan innocently believes is a mythical monster, rather than a part of the female genitalia. Mr. Mackey later holds a rehabilitation session with the kids to teach them to not use foul language ("It's Easy, Mmm'kay").
After watching the film again, Cartman and Kenny argue over whether it is possible to light farts on fire like Terrance does in the movie. Accepting a $100-bet, Kenny tries it and, predictably, catches fire. An ambulance promptly arrives at the scene to try to help Kenny, but it is suddenly rammed out of the way by a salt truck, which then pours the salt on him, which puts the fire out. Despite that, though, Kenny later dies because Doctor Gouache accidentally replaced his heart with a baked potato, giving him three seconds lifespan after revival. Kenny's soul tries to get into Heaven, where there are thirty odd naked women waiting conspicuously, but his access is denied and he ends up in Hell ("Hell Isn't Good").
After hearing that the boys went to the movie again, their parents ground Stan and Kyle for 2 weeks and Cartman for 3 weeks. The news of Kenny's death prompts Shelia and other mothers to begin protests and form "Mothers Against Canada" or "M.A.C." ("Blame Canada"). Instead of simply banning the show in the United States, they arrest Terrence and Phillip on Late Night with Conan O'Brien (making Conan kill himself in the process). At the United Nations, the problem escalates when the Americans blatantly and rudely refuse to return Terrance and Phillip (the U.S. representative gives the ambassador the bird and says "Fuck Canada") despite the plea from the Canadian ambassador saying that their economy depends on Terrance and Phillip. The American then openly laughs at the Canadian accent. Enraged by this, the Canadians respond by bombing the residence of the Baldwin brothers. President Clinton then declares war on Canada and orders the execution of "war criminals" Terrance and Phillip within two days. When Sheila, who has become the U.S. Secretary of Offense, overhears Cartman admonishing her ridiculous measures ("Kyle's Mom's a Bitch"), she forces him to have a V-Chip placed in his brain by Doctor Vosknocker in order to prevent him from using profanity and swearing, much to his chagrin - every time he swears he gets an electric shock. With Terrance and Phillip set to be executed, Kyle, Stan and Cartman decide to form La Resistance and get the message out to the children of South Park, with the promise of punch and pie ("What Would Brian Boitano Do?").
Meanwhile in Hell, Satan has been torturing Kenny until Saddam Hussein appears and reveals that he is Satan's lover. When Satan discovers that a war has started on Earth, he says with delight that it has been prophesied that he can return to Earth once the blood of "these two Canadians" (who are, by Satan's accounts, innocent) touches American soil. Saddam makes no secret of the fact that he wants to rule the Earth (as well as do nothing but have sex with Satan, which Satan doesn't want), but Satan can't stand up to him ("Up There"). Kenny decides to try and help Satan while stopping Saddam, so he goes to Cartman, as a ghost, to try and get him to stop the executions.
Cartman tells Stan and Kyle at the meeting that Kenny visited him, warning him that Satan and Saddam Hussein will take over the world if Terrance and Phillip are executed. The boys are surprised to see Gregory, who can help. The gang's speech does not impress the rest of the children until Gregory (who knows what the boys are trying to say) comes up with a daring plan to rescue Terrance and Phillip. Stan, who is concerned that Wendy will like him more than Gregory if he is more "political" and volunteers to go on the mission ("La Resistance"). Stan, Kyle, and Cartman are sent to find "The Mole," a French boy who agrees to help them rescue Terrance and Phillip, who are to be executed in the electric chair during a USO show. With Canadians being taken away to "death camps", Kyle is forced to hide his adopted Canadian brother Ike in his attic.
Back in Hell, Kenny suggests Satan should leave Saddam for good. Although Satan initially agrees Saddam convinces him that he must go back to earth Earth so that they can rule together ("I Can Change"). As a result, Satan cannot bring himself to break up with Saddam and they head for the surface - much to Kenny's annoyance.
The USO show begins, and the boys begin to carry out the plan by stalling Big Gay Al's act ("I'm Super"). Cartman, tasked with turning off the power shortly before the execution begins, is frightened when the ghost of Kenny again warns him that Saddam and Satan are on their way. Cartman runs away without turning off the power, causing the Mole to be spotted and mortally wounded by guard dogs ("The Mole's Reprise"). Kyle and Stan desperately run to the stage to prevent the execution, but Kyle cannot bring himself to stand up to his mom and Sheila orders it to start.
Before it can start, though, the Canadians launch a surprise attack. Cartman rushes to turn off the electric chairs and receives a mild jolt that causes the V-chip to malfunction. The Americans and Canadians start battling each other. Stan runs after Terrance and Phillip, but a bomb goes off and the splash damage sends Stan flying face first into a puddle, while also knocking him unconscious. He regains consciousness and finds the "clitoris" which in this case turns out to be an all-knowing entity resembling a gigantic disembodied version of the anatomy part. The clitoris tells him to save Terrance and Phillip. He asks about Wendy, and the clitoris tells him to be confident because "chicks love confidence". Sheila watches the war, still convinced that M.A.C. was doing the right thing, but the other members leave angrily saying it has gone too far. Terrance and Phillip try to escape but the American forces and Sheila corner them.
Just as they are about to be killed, Stan, Kyle, and the rest of "La Resistance" stand in front of them. Kyle finally decides to stand up to his mom and says he wants her to stop fighting all these battles and just be his mom, and that she shouldn't blame Canada because it's his fault that he saw the movie in the first place. The American forces, seeing that Kyle has a point, decide not to fight anymore, but Sheila - still refusing to admit any wrongdoings - shoots Terrance and Phillip anyway. When their blood touches the ground, Satan and Saddam burst out from Hell and begin wreaking havoc, followed by Kenny, who takes advantage of the situation to return to Earth. The American forces try to kill Saddam by shooting him, but his body is bulletproof. Despite Sheila being shocked to see what she has done to the Earth, Satan is quickly pushed aside by Saddam who makes everyone, including the Canadian and American forces, bow down to him while Satan watches. Kenny insists to Satan that now is the time to stand up to Saddam, but Satan can't bring himself to do so. Saddam orders a big statue of himself, exactly where Cartman (whom Saddam calls a fat kid) is standing. Cartman protests, discovering that the V-chip's malfunction gives him the power to shoot electricity from his hands whenever he swears. He does with gusto and attacks Saddam with multiple massive bursts of energy for calling him fat - finishing off with a long tirade of swearing (including "Barbara Streisand"). Saddam calls for Satan to help to kill Cartman, but Satan, finally tired of Saddam's abuse, angrily confronts Saddam, and kills him by throwing him upon a pointed, jagged rock in Hell.
Satan thanks Kenny for his help and offers him one wish. Kenny, despite the chance to come back to life, wishes for everything to return to how it was before the war - much to the army's and the boys' surprise. Satan grants his wish and returns to Hell, taking Mr. Garrison's puppet Mr. Hat as his new friend. The boys thank Kenny for his sacrifice, saying he's a "real pal". Kenny then takes down his hood for the first time, says goodbye, and disappears. Everything returns to normal; Sheila apologizes to Kyle for not paying attention to him and decides to end her anti-Canadian protest for good. Wendy suddenly kisses Stan, admitting she never liked Gregory. Canada and the United States become friends again, and everyone joins hands and sings about their happy ending ("Mountain Town (Reprise)"). At the end of the number, the boys see what appears to be a meteor shooting from the ground - Kenny's act of sacrifice was enough to get into Heaven. Sprouting wings and a halo, he enters Heaven (and gets the thirty odd naked women).
A brief "bonus scene" after the credits shows Ike eating a mouse while waiting in the attic for his mom to return.