Very cool....
we had an odd one at our school...we cemented gnomes (yes, the garden ones) everywhere, drew the crime scene outlines for dead bodies all over the school - walls, ceilings, raised walkways, everywhere! in pink paint, filled the headmasters office with sheep and kidnapped a year 9 boy who pissed us off (with the assistance of one of our geography teachers who he also pissed off) - we ran in, sellotaped him to his chair, put him in the back of a van and sped off...
We locked the gates shut in the evenings too, so that then all the buses came to collect everyone from school, 6 of them got trapped in the yard and they had to cut the chains off...
did i mention we were drunk too...Bloody good day!