Any South Park fan worth their (chocolate) salt(y balls) knows the disclaimer at the beginning of the show off by heart.
"All characters and events in this show - even those based on real people - are entirely fictional."
But creators Matt Stone and Trey Parker weren't just making a throwaway joke, they were protecting their backs. Because pretty much everyone in, around, and near South Park is based on someone the pair knew in real life. Don't believe us? Check it out.