The plot follows Stan Marsh, Kyle Broflovski, Eric Cartman, and Kenny McCormick as they sneak into an R-rated film starring the Canadian comedy duo Terrance and Phillip, after which they begin swearing.

When the consequent moral panic culminates in the United States declaring war on Canada, Stan, Kyle and Cartman take it upon themselves to save Terrance and Phillip from execution, while Kenny tries to prevent a prophecy involving Satan and Saddam Hussein's intent to conquer the world.

South Park: Bigger, Longer & Uncut premiered at Grauman's Chinese Theater on June 23, 1999, and was released theatrically in the United States and Canada the following week by Paramount Pictures, with Warner Bros. handling international distribution.

One morning in South Park, Colorado, Stan Marsh, Kyle Broflovski and his adopted brother Ike, Eric Cartman, and Kenny McCormick visit the movie theater to see Terrance and Phillip's R-rated film, Asses of Fire.

As per a bet with Cartman, Kenny sets his fart on fire (imitating a scene from the film), accidentally immolates himself and is rushed to the hospital, where he dies from a botched heart transplant.

Terrance and Phillip are arrested as war criminals; when the United States refuses to release them, Canada bombs the Baldwins in retaliation.

Unable to reason with their mothers, Stan, Kyle, and Cartman form a resistance movement with their classmates to rescue Terrance and Phillip.

[9] The William Morris Agency, which represented Parker and Stone, pushed for the film's production to begin as soon as possible, while public interest was still high, instead of several years into its run, as was the case with Beavis and Butt-Head Do America (1996).

Isaac Hayes reprised his role as Chef, and audio samples of staff children Jesse Howell, Anthony Cross-Thomas and Franchesca Clifford were used for the voice of Ike Broflovski.

Guest voices for the film include George Clooney as Dr. Gouache, Brent Spiner as Conan O'Brien, Minnie Driver as Brooke Shields, Eric Idle as Dr. Vosnocker, and Dave Foley as brothers Alec, Billy, Daniel and Stephen Baldwin.

Mike Judge, creator of Beavis and Butt-Head and King of the Hill, provides Kenny's voice in his sole speaking appearance at the end of the film.

[9] Although initially denied by Paramount, Metallica vocalist James Hetfield performs the track "Hell Isn't Good", which was confirmed by Parker in the 2009 Blu-ray commentary.

Characters and individual scene elements were designed with texture mapping and shading that, when rendered, resemble the cutout animation of the short films and the series' first episode.

[14] "By creating flat characters and backgrounds in a 3D environment, we are able to add textures and lighting effects that give the film a cut-out construction paper stop-motion style which would have taken many more months if done traditionally," stated line producer Gina Shay.

[26] "I'm Super" recalls "Be Our Guest" and South Pacific's "Honey Bun", and "Kyle's Mom's a Bitch" echoes Chitty Chitty Bang Bang; "Up There", "I Can Change" and the "Mountain Town (Reprise)" recall The Little Mermaid's "Part of Your World", "Poor Unfortunate Souls" and "Part of Your World (Finale)"; and "Uncle Fucka" also drew comparisons to Oklahoma!, particularly in its coda.

[11] The soundtrack received critical acclaim, with Entertainment Weekly describing it as "a cast album that gleefully sends up all the Hollywood musical conventions we're being deprived of".

[1] The film was rated R for "pervasive vulgar language and crude sexual humor, and for some violent images" by the Motion Picture Association of America.

[31] This was a result of an industry-wide crackdown on such attempts, as proposed by President Bill Clinton in response to the moral panic generated by the Columbine High School massacre two months before the film's release.

[34] In the aftermath of Columbine in relation to the film's release, Parker was questioned whether he felt "youth culture [was] under fire", to which he commented: "[I]t's amazingly strange, because that climate is what the movie is all about, and we wrote it more than a year ago.

"[35] Hayes responded to conservatives urging prudishness as a cure for society's ills: "If we give in to that and allow [entertainment] to become a scapegoat, you might wind up living in who-knows-what kind of state...

During the interview, Parker and Stone showed a clip of the film in which O'Brien (Brent Spiner) hands over Terrance and Phillip to the US government before committing suicide.

It was initially reported that on the day of the Columbine massacre, a friend of the perpetrators, Chris Morris, was seen wearing a black T-shirt depicting characters from South Park.

[29] South Park was also, at the time, generally waning in popularity: ratings dropped nearly 40 percent with the premiere of the third season and, according to Entertainment Weekly, "it [wasn't] the pop-culture behemoth it was last year [1998]".

[49] IGN's Scott Lowe explained, "Although clearly aged, South Park: Bigger, Longer, and Uncut looks great and is free of the washed out, compressed imperfections of previous standard definition releases of the film.

[54] Audiences surveyed by CinemaScore gave the film a grade "B−" on scale of A to F.[55] Rita Kempley of The Washington Post described it as "outrageously profane" and "wildly funny", writing that "While censorship is the filmmakers' main target […] [Parker and Stone's] favorite monster is the Motion Picture Association of America, self-appointed guardians of the nation's chastity.

"[56] Stephen Holden of The New York Times regarded the film's "self-justifying moral" as "about mass entertainment, censorship and freedom of speech."

"[58] Writing for The Washington Post, Michael O'Sullivan neutrally regarded the film's offensive nature, commenting "Yes, the lampooning is more broad than incisive, but under the bludgeoning of this blunt instrument very few sacred cows are left standing.

Ebert rated the film 2+1⁄2 of 4 stars, calling it "the year's most slashing political commentary", but also wrote that "it is too long and runs out of steam, but it serves as a signpost for our troubled times.

In response, Parker and Stone ridiculed him in two consecutive episodes of the series' fourth season: "Cartman's Silly Hate Crime 2000" and "Timmy 2000".

[90] In 2007, during development of the "Imaginationland" trilogy, Parker and Stone described the possibility of producing it as a film, but ultimately abandoned these plans amid a demanding production schedule.