When I was a sophomore in high school (which housed jr high in the same building), the president of the graduating class was also a student aide (and National Honor Society member, etc), which gave him pretty much unfettered access to the front office. He often made the announcements over the intercom. This of course gave him "means" and "opportunity."

He supplied his own motive.
Late one afternoon a day or so before the end of school that year (which pretty much amounted to babysitting, since finals were over), he strolled into the office, picked up the microphone and announced to the school, "All 7th and 8th grade students report to the gymnasium immediately for a special convocation."
Of course there was no convocation. The Jr High students, delighted to do anything but sit in the classroom, promptly stampeded for the gym. About half the Jr High teachers realized instantly they were being had and were able to leap to their classroom doors to cut them off at the pass. However, the other half were either slow to think or slow to act, and a couple hundred kids went running down the hall (past the shouting principal) and stormed in on the surprised gym classes. Chaos reigned for about 15 minutes before everyone was herded up and corralled back in the classrooms.
Mr. President's sentence for this transgression was to dust all the athletic trophies in the display cases between the last day of school and the graduation ceremony. We knew this because as part of his graduation speech, the thanked the janitors for their supervision during his sentence.
I suppose nowadays he would have been expelled, had his diploma yanked, and probably jailed for something.
I hesitate to say what my buddies and I did for our graduation, as I am not sure what the statute of limitations is. The teachers then were cool with it, but who knows what kind of clowns are running good ol' BCHS now...
