I remember one year, I think the Year 12s of 2008, part of their muck up "day" or "week", first they went into assembly which was in the sports center, gave the Headmaster a farm animal, then let loose tons of goats/sheep into the sports center, they pooed everywhere and they got yelled at in front of the school and gotten taken outside, and throughout the rest of assembly you could hear the teachers yelling. They also had water bombs and threw it at people as well as the actual muck up day, they made all the traffic from the highway into our school then made all the teachers park their cars in the Junior school and walk the massive hill while those who had their Ps parked in the teacher's car park, as well as put honey & foam on toilets and garbage bins, put the pirate flag on the flag pole as well as put a "For Sale" sign. The best Muck Up Day. After that, the school said that if anyone does this sort of thing again, then they will be expelled or suspended.
When my mum worked at my school, the Year 12s put a dead fish in the library as well as stacked a room of tissue boxes in the office of the previous librarian who wouldn't allow people to use tissues to blow their nose and she was really strict.