I've also come across a fanfiction that has Randy Marsh as a sort of bumbling Jedi in training. He's in the Star Wars universe and has to deal with all the Jedi traditions while still being his South Park self. It's a really interesting take on mixing the two franchises, and the author does a great job of writing Randy's character in this new and strange setting.
There's a fanfiction where the South Park kids accidentally time - travel to the Star Wars universe. They end up causing chaos among the Jedi and Sith alike. It's full of humorous misunderstandings and wild antics. The story plays on the differences between the two universes really well, like how Cartman tries to use South Park logic in the Star Wars world.