Spitballs were pretty much a critical part of jr high & high school.
We had one teacher that everyone picked on for whatever reason. Every time that poor guy would show us a movie, the tv would be covered in spitwads. Not to mention his blackboard, desk, and window blinds.
There was a math teacher that everyone hated pretty bad at my highschool, too. I watched this guy chew up an entire sheet of paper, and launch it at her blackboard. It made an awesome sound, and freaked her shit out bad. It was glorious, I tell you.