i’ll start:
In my senior year, some kids somehow snuck into the school at night with two ceramic toilets (unclear if they were stolen from the boys bathroom or brought in) and put them in the fucking trees of my school mezzanine. My school was two stories high, so on the second story you could look out and a toilet would be a just few feet away. No one has any clue how they did it, or who “they” is.
Another one, a friend that went to a different school dyed the school pools (for swim team) purple with buckets of food safe dye. They had to drain the entire pool, and as swim team classes were in first period, a few people jumped in before realizing. They got to go home early because they too were now purple. My friend never got caught!