"Come on down to South Park and meet some friends of mine!" --From the intro theme by Primus.
Nothing, not even the show itself, is safe from being lampooned on this 'toon. Unfortunately the shock value has been waning, as the past few seasons have sought (and acheived) new heights of rudeness. And the show's running parody of TV script formulas ("I learned something today...") has long been tediously formulaic. Not much left for the show, I fear, but to recurse into parodies of its own rudeness (definitely not a show for kids!).
But I find the treatment of current events sometimes ingenious, and the characters' forthrightness is a refreshing contrast to the socially-acceptable dialogue found in most entertainment. The characters say exactly what they mean, no mincing words. The show owes a huge debt to The Simpsons, as the creators said their goal at the outset was to create the same kind of spontaneous absurdity.
Kenny's muffled and horribly crude dialogue is actually understandable, depending on one's level of intoxication. The kids' unrestrained swearing is the closest I've seen on TV to how I remember kids actually talking.