One of the things I miss most about being in art school was... the casual graffiti. Students of all stripes have a tendency to make flyers, deface signage and scribble on bathroom walls, but no student does it with the flair of an art student. From the relatively lowbrow "Pratt Industrial Design Diplomas - Take One" drawn over the toilet paper roll in the men's bathroom, to more intricate fare like a flyer in the dorm stating "I lost my keys - they look like this" hovering over a photorealistic drawing of their entire keychain, there was plenty of creativity going on outside of the classrooms.
As for in-classroom creativity: While these may or may not be from art students, Student Beans has compiled a list of the best textbook and exam-paper defacements they could find from around the globe.
They vary in quality, but they all have that twisted art school vibe. Click here to check them all out, but beware that some are outright disturbing—we've posted the tamer ones here—and many are NSFW!