When i was 13-14 i was messing about with some friends out at a shelter on our schools pitch, i climbed up on it but had to get off just as soon because a teacher was doing rounds around the school (we weren't allowed on the shelter for our own safety).
Problem is getting down isnt as easy as getting up (strangely enough). Its a good 3 meters up and i was pretty short... so i tried to hang over the edge and drop down... instead i ended up doing a pendulum swing forward, lost my grip and fell 2 and 1/2 meters flat on my back..
My friend being as mature as he was, laughed himself to a near seisure and thoguht it would be even better to squat over me and let out a real ripper off over my face. This was at lunch and everyone from my year were watching... even the teacher started to laugh. I was having dizzy spells for a week afterwards, most likely the fall but that fart was particularly rancid.
This is a tie with another moment i had in school... we had a part time teacher who was solely used by students for abuse. everyone in the class would join in on his torment, but i was sort of shy and innocent. But after a while even i felt like joining in, his reaction was priceless. So i rolled up some tin foil from my lunch box and hurled at him when he wasnt looking. Little did i know the Principle of our school decided to check on us at the exact moment the tin foil left my hand. I nearly shit myself. He didnt say anything, just pointed at me and gestured to come with him. The class erupted with laughter when he closed the door. I sort of laughed too... didnt help in the slightest.