Oh haha.. I remember a joke like that too!
Oh this happened in my nephew's school, 4th graders. A bunch of students reported their books were missing and everyone was puzzled until the teachers checked their lockers. Their books were not missing, they were just drowned underneath A2 or A3 sized art papers and other stuffs. The lockers are not designed to fit the art papers and after their art classes, the boys just chuck them into the locker the best way they could and most times they are crumpled and stuffed on top of the books :D