Ah, what didn't we do! We wern't known as "bad kids", so nobody supspected us
. A few I can remember;
This is actually at college. We tied a freinds shoelaces up to a pencil, then he went into the lift and we made the doors close so that the pencil was outside the lift. So, the pencil attached to the shoelaces was securely fixed by the lift doors (this is hard to explain, but seemed the obvious thing to do at the time). Then, with us inside, we sent the lift down. It started to tighted his shoes a lot, then the shoelace actually got pulled apart. We later found the pencil had been flung quite a way by the force built up then released (we expectecd it to snap)
At school, we often threw pieces of fruit (don't ask), and a freind who is actually a good cricket bowler went to throw an orange at someone, and it missed or he moved, and it splatted all over a teacher's car window. Came up in assembly the next day
Apple through the wire fence was always a good one, comes out like chips
We manufactured fake sick from sandwiches and water (works rather well) and poured it so it looked like someone had ran to a bin throwing up all the way, it was also all on the top of the bin. Was hard not to laugh when we saw everyone leaving school and trying to avoid the "sick" (was accross the main exit)
A remember something involving lots paper planes out of a window, but can't elaborate as I can't remember much.
Can't think of many at the mo, will come back to this
EDIT, oh yeah, another nice and simple one. There was this drawer in a classroom labelled "pens, glue, etc". We quite convincingly added an "i" between the "n" and "s" of pens as there was an unusually big spacing there. Apparently, when the teacher noticed some days later, she read it out loud without thinking