Best University prank ever, courtesy of my brother:
A friend lived in the third floor of a block of flats. Half of his friends took him out to get battered and have a good night.
Meanwhile, the other half took all the items from his room downstairs to a room on the first floor, so it looked identical. At the end of the night... the very, very drunk victim was returned to his 'room' on the ground floor and put to bed... where he proceeded to fall asleep.
Twenty minutes later, the three most burly friends busted into his room wearing balaclavas, and proceeded to throw him out of the window.
The screams were heard for miles, allegedly