Some very intelligent and wise people already mentioned Psychonauts, Earthworm Jim, anything from Douglas Adams, King's Quest, and Conker. Also some parts of MDK, Destroy All Humans, Tass Times In Tone Town (from before you were born, kids,) Jazz Jackrabbit (even more before you were born,) and Commander Keen (even more...) Did anyone mention Zork? I think someone mentioned one of the Zork games.
Even the guys who made Goat Simulator expect people to get bored with it after a couple of hours. How does that compare with Psychonauts which is still better than 95% of the games currently available and at least equal to the rest.
As for the South Park game, that is definitely an acquired taste, like scatophilia.