School
As the slightly rotund unpopular kid at school I more often than not fell into the trap of taking on stupid dares to gain popularity, so I've got quite a few of these.

The first that springs to mind was French class, circa Year 9. Fat Freddy had been robbed of his very expensive new trainers that he was not really supposed to be wearing but had 'medical reasons' for doing so. More accurately he had been robbed of one trainer and said trainer was doing a very good impersonation of a ball as it was thrown around the classroom.

When it reached me, someone shouted 'Throw it out the window', which quickly becoming chants of 'Window! Window! Window!' With little hesitation and desperately snatching at a chance to be popular for a nanosecond I took aim and launched the trainer full pelt at the window.

Only for someone with quicker reactions than me to reach across and slam the window shut. Now if there's one advantage of being fat, it's strength and there was no way this high speed bullet trainer was being stopped by a pane of glass. Smash! Straight through the glass, out of the 3 storey building. Worse still, it didn't seem to lose any speed as it hurtled to the ground to arrive very non-discretely on the bonce of our French teacher.

Oops. Nearly got excluded for that one.
(quantum raspberry quizzically quashing Quebecans, Thu 1 Nov 2007, 12:53, Reply)