At Uni I was in Halls of residence for the year I was there. It was a group of rooms, 18 to a square with communal bathrooms in the centre and a kitchen at one end.
The doors would spring open if you kicked them just by teh lock, thgis led to numerous pranks,
1) The usual 3 o'clock in teh morning, burst in and dump said occupant in a freezing cold bath
2) unscrew teh hinges so when occupant came home and opened teh door with teh key the whole door would fall into teh room.
3) and this was the best, one lad had to go home for a fortnight due to a family thing. we broke into his room, now in each room you were given one of those 2' x 3' long shagpile rugs. We watered and grass seeded it and grew a lovely 'lawn' in his room, teh day he was due back, we borrowed a student uni mini bus and went up Snowden(I was at Bangor).We nicked a sheep off the mountain and stuck it in his room. When he came back he opened his room to find the sheep happily munching on his new lawn!
( We took teh sheep back and it wasn't harmed in teh making of this prank!)
Then there were teh times at work, we used to get stuff delieverd in big boxes filled with those polystyrene S shapes. One lad made teh fatal mistake of leaving his car keys lying aroudn so we opened a window, locked teh car and then filled it to the brim with the stuff.
One played on me when I worked at the Britannia, By the kitchens there is a big extractor fan that blows teh hot air out from teh kitchen. I worked out that in winter if you parked under it your windscreen didn't get frosted up for when you finished work so I sort of made this my 'space' I also used teh same spot in Summer.... Thats when the sods used 3 Catering sized rolls of Cling Film to completely wrap my car up. What they hadn't realised was that teh heat from teh extractor actually turned it into shrink wrap! It took me about an hour with a sharp knife just to get in teh car!
I've got some more but I'll leave them for later