What was the best one in your school?
There's always been a running legend in ours that some dude got some Pottasium from the chemistry store cupboards, and, on muck-up day, started throwing chunks into the school toilets. So bathrooms exploded and the genereal level of chaos was sufficiently satisfactory to get a good laugh from the leaving class.
We weren't so adventurous on our last day, but:
-glued all the chairs in the 6th form centre to the floor (hilarious);
- somebody put mild laxatives in all the water coolers.
-used salt as a sugar substitute in the sugar pot for staff's coffee break
-glued one-pound coins in random outdoor areas of the school (simple, but effective, as almost everyone who passed by tried to pick them up. Video footage of this one!)
-strategically placed water balloons.
-One of my mates lived on a farm, so we got pigs in and let them loose: one had a number 1 pinned to it, the other had a number 2, and the third had a number 4. We just sat and laughed as they tried to search for number 3.)
Needless to say, I guess the school was glad to get rid of us.