Acceptable Targets: Simply put, everyone and everything that has, does and will exist ever. However, unlike most works that try to invoke this, they take complete responsibility for what they write and who they mock, always making their message clear, with the belief that it's hypocritical to say that anything can't be made fun off while others can.
Crosses the Line Twice: If their names are attached anywhere on a work, then assume that it's going to do this at least once.
He Panned It, Now He Sucks: When Isaac Hayes left South Park after the Scientology episode, Trey Parker and Matt Stone were quick to point out that they had poked fun at several other religions and he never seemed to have a problem with it before.
Due to his stroke (which he had right before he quit the show), his willingness to poke fun of others before (he had even stated at much), and Scientology's internal policy of dealing with criticism or jokes directed toward it, some believe that it wasn't entirely Hayes's decision to quit the show. The episode in which his character Chef was Killed Off for Real also features Kyle pointing out at his funeral that they should not hate him for what he did, but rather, they should hate the "fruity little club" that made him that way.
This seems to be confirmed, as of a 2016 Hollywood Reporter interview with his son.
Ho Yay: They've pushed their Heterosexual Life-Partner status to its logical limits, often referring to themselves as "a married couple" and, on at least one occasion, passionately making out. It has reflected on their work, as seen in South Park.
Memetic Mutation: "Derp" has become a very popular word in rage comics, where it is usually used as a substitute for names.