In the end of middle school, the 9th graders:
1. Started a Food Fight
2. Put mysterious suitcases in front of classrooms
3. Ripped the fire detector out of the wall in a bathroom, setting off the alarm, and making us wait outside the school for the rest of the day while the fire department checked it out.
At the End of my 10th grade year, the seniors took apart a car, carried the parts inside, and rebuilt the car in the middle of the commons. It was funny as hell!