I thought the same back in the day.
Then, at college, my friends wanted to go see the movie.
I was aware of south park but never really "watched"-watched it. I zapped through it sometimes, watched a minute or two, didn't get it and moved on.
Then we went to see the movie, mega-high on pot.
I nearly pissed my pants. In fact, I did pis my pants a little bit
I literally had stomach ache from laughing.
That opening song with Terrance and Philip.... my god.
I don't remember ever having laughed as hard as in that theater.
I'm guessing the pot had a hand in it though.
But dude seriously....... I even missed plenty parts of the movie, simply because I was laughing that hard.
It totally blew my mind.