take all the junior and teachers liscense plates off and throw them in the pool, then hide the screws in random places through out the school
if you have a multi level school, buy a bunch of dixie cups and fill them w/ water and cover each inch of the stairs, so no one can go up or down!
another one but not quite as fun is to get a huge rug/volleyball net and set it up inside the lunch area and have a huge v-ball match.
Facing your biggest fears, and being honest with yourself, and everyone around you makes you stronger and more respected. Stay true, dont hate, show love, and change the world.