20. South Park: Bigger, Longer & Uncut (1999)
After the rise of South Park on TV in the late '90s, it seemed inevitable that creator duo Trey Parker and Matt Stone would find themselves helming a movie version of their immensely popular show. Alas, what could have been overindulgent or unnecessary actually provided the pair with the opportunity to create the best South Park episode yet - albeit one that ran 90 minutes, instead of 22.
Whereas The Simpsons Movie failed to do the show's glory years justice, South Park: Bigger, Longer & Uncut is a bonafide gem; filthy, controversial, ridiculous and insanely funny. The plot here centres on the boys - Stan, Kyle, Cartman and Kenny - as they're thrown into an increasingly bizarre set of circumstances that sees the US going to war with Canada and Saddam Hussein's gay relationship with Satan.
The jokes come fast and thick: some brilliantly satirical, some plainly stupid (a smart gag is frequently followed with a fart joke). Of course, Parker insisted on rendering South Park: Bigger, Longer & Uncut as a fully-fledged musical, and indeed, it's the Broadway-inspired showtunes that cement the picture as truly great slice of comedic gold.