Oh, it's a fun challenge that people do in fandoms where you're challenged to write some kind of fic, but it has to be a certain amount of words--generally, the required word count is either 10,000+ or 15,000+ (so, longer fics) and then you're matched with an artist who does some kind of art of your story. It's really neat!

(Haha, sorry I assumed everyone would just magically know what it was, I shouldn't have.)