Get a mess of copper BB's and roll them across the floor.
Spitballs.
Mess with his desk. Tape stuff down. Hide things.
Take all the chalk/whiteboard markers.
Alternately take all the colored markers leaving only black, and take everything that can be used to erase the board.
Release large flying things in the room. Cicada, moths, mosquito hawks, anything.
Assault his other senses. Strong colognes, air fresheners with strange scents, hunting lure (deer piss), stink bombs.
Figure out a way to rig the lights to go off without you being out of your seat.