Where to start?
Throwing fruit around a classroom (the teacher was absent) I ended up as a teacher in the room many years later and the chalkboard still had this circular mark and smear from the orange that hit it and slide down. I used to smile everytime I say that, made my day(s) years later.
Two boys decided to hide in a cupboard and spring out to suprise a teacher on 1st April. I slid (quietly) a broom handle across the cupboard to prevent this and wrote a note for the teacher. The teacher and I then acted as if the boys were not there despite the muffled cries from the cupboard. oh the hilarity of the event as the boys had told me to tell him they had gone surfing for the day. He put on a good performance as "irate teacher about to suspend boys". It was a very small year 12 class.
Same absent teacher (turns out the pub was too close and too inviting) was our science teacher and left us in the lab one lesson. So out came the tea and biscuits, using the lab equipment we made tea in the glass beakers.
Then another time (it took a while for them to get rid of him) we sent up an electrical device which the boys damaged enough to get a current through. Much mirth as we zapped passer bys.
We did not fully understand the killing capacity of electricity.
I was also a complete bitch to one boy for which I am truly sorry and would like to take it back if I could. I was an appalling 14 year old.
Back in the semi dark ages of feminine hygiene there were these devices with cremated the offending objects and one lunch, tired and not wanting to do double english a group of us overloaded on and set off the fire alarms.
Apart from that lie, cheat and kiss boys in the secret corners. We did get permission to have a home room in year 11, in which we could play music etc at recess and lunch, which promptly became the truth and dare room followed rather shortly by the no longer the year 11 room.
Now as a teacher I tell the kids there is not much they could think of doing that I have not already done.
"The two most common elements in the universe are hydrogen and stupidity." --Harlan Ellison