Craig and Tweek have been going to the same school forever. However, it's not like the two ever really... Noticed eachother. Hell, they didn't even realize the other existed. But hey, that's what happens When one never even shows their face in any classes (Craig).

Craig was upstairs. Nobody really went up there, so that's where he did most of his schoolwork.

But one day- Tweek was sent to to grab some things for an art class. He walked upstairs, looking around as he went.