After twenty seasons it's clear that South Park is one of the most successful shows of all time. It's a behemoth, crashing through everything without a care in the world.
Weirdly, though, the show actually started as a Christmas card. You might know that the first South Park short was a Christmas special, featuring Frosty the Snowman, Santa and Jesus, but you might not have heard that it was sent around on VHS tape (when those were still a thing) as a gift for some fancy producer's friends.
This was revealed in an interview with Entertainment Weekly, when South Park's creators shared the story of how they met a Fox executive producer at a screening of their indie film Cannibal! The Musical. He asked to see everything they'd done, so they showed him a short they'd made - it looked a bit crappy (as you can see), but he loved it.
The producer copied it onto tapes and sent them to his friends, then the next year gave Trey and Matt a couple of grand to make another version.
This one went nuts - there were rumours that George Clooney made 300 copies to hand out - and from there the creators scored a heap of meetings to turn the short into a full length show.
The rest, as they say, is history.