In my school, whenever we had an assembly, every grade sat in a separate section of the gym, and at the beginning of every year, we had an assembly.
At the beginning of my senior year, several seniors brought bulk bags of bouncy balls, distributed them to several other seniors and juniors, and at the end of the assembly, threw them all at the freshman area.
Seeing hundreds of balls bouncing on one room is quite a site.
Though several people were hurt and the principal was pissed
I didn't have a problem as a freshman though