I don't know what they might call it, but does your school have it?
It is when on the last day, the Sixth Form play pranks around school & that sort of thing.
Yea we have senior pranks too. Usually it's one huge prank, 2 years ago they got the key to all the locks and they glued them all shut.
We also have Senior Water day, where throughout the day seniors just spray everyone with water guns/buckets of water.
They canceled muck-up day at our school because people spray painted shit and put a potato in the principals exhaust and it blew. Now im in the year for it, and i dont get it. wow.