We're not supposed to expect much depth from summer movies, and even less from an animated feature starring foulmouthed characters who move with the delicacy of bouncing Popsicle sticks. But, omigod. ''South Park: Bigger, Longer & Uncut'' turns out to be the funniest, most risk-taking, most incisive movie of the summer, never mind that the summer is young. And the promulgators of fancier culture might take a few lessons in courage from "South Park" creators Trey Parker and Matt Stone.
Anyhow, who knew? Parker and Stone's ongoing "South Park" on Comedy Central -- hilarious as it can be -- has been wildly uneven, and Parker's dorky previous films "Orgazmo" and "Cannibal: The Musical" didn't exactly shoot flames of glory. Yet the characters in "South Park: Bigger, Longer & Uncut" move with, may I say, asses of fire -- to crib the name of the deliriously scatological movie small-town prepubescents Kyle, Stan, Kenny, and Cartman sneak into. The boys emerge with a vocabulary so obscene, it sends the mothers of South Park, Colo., into a frenzy of blame laying.
Finger-pointing leads to war. Cartman is forced to test an anti-obscenity V-chip implanted directly into his corpulent self. Kenny, meanwhile, goes to hell, where Satan and Saddam Hussein are bedmates, but that's another story, and it's not for kids.
"Bigger, Longer & Uncut" dive-bombs such up-to-the-minute targets as Bill Gates, Jar Jar Binks, and parental responsibilities in a post-Littleton society. The plot rollicks ahead with few dead spots. And the inspired musical numbers (by Parker and Marc Shaiman) brilliantly parody/ honor the conventions of Broadway show tunes and, especially, the Disney-formula ditties of Alan Menken. If I dock the movie half a grade, it's only because, in spite of everything, I still believe in the possibility of other liberating, less poo-poo-driven comedies that don't star characters made of construction paper.