I was thinking maybe I'd share some of my favourite SP fics on here, mainly from FF.net but perhaps some from deviantart as well - I haven't really looked at any from tumblr.
It can be hard to find really good reads, but I've occasionally stumbled upon some superb pieces. So I'm going to go ahead and post the link to one I'm currently reading:
http://www.fanfiction.net/s/6336883/1/Im_Bored_Youre_Amorous Title: I'm Bored, You're Amorous
Author: ~
PachucaSunrisePairings: Bunny, Candy, Style (in order of prevalence)
Premise: "When Cartman finds out that Butters has a crush on Kenny, he comes up with a nefarious scheme: make Butters believe that Kenny is in love with him. Butters/Kenny, CartmanxWendy, and Stan/Kyle." - the author
Basically, the grammar/spelling is virtually perfect, the writing flows excellently, and the dialogue is incredibly realistic - no South Park humor is lost here!
So I'd definitely give it a read if you're into reading SP fics!