my $.02
So many pranks, where to begin....
Back in the day when I was in Boy Scouts spending my summers working on camp staff the bane of the staff was morning flag raising. Had to get up extra early before breakfast and more importantly before coffee. That year many of us were not what you would call morning people so a few of us took it upon ourselves to make the last weeks flag raising a little more interesting for the staff. I digress, at the camp I worked at, the flag pole was in a large grassy area opposite the commissary. The commissary was a rather large building with a very big sloping roof. During the flag raising the staff stood behind the flag pole facing the commissary while all the campers stood with their backs to the commissary. So cut to the last week of camp, on Thursday night a few of us 'borrowed' the keys to the chow hall and made off with a 50 pound bag of flour which we then hauled to the top of the roof and wrote, "Good Morning Staff" in big letters and drew a smiley face, (we had some extra flour! Fortunately for me I slept in and missed the hilarity and guilty looks that would have sealed my fate. Those who were there had to clean up the mess and spend an extra day or too doing it during the hot North Carolina Summer. Ahh good times...
My other all time favorite prank was when I was studying abroad in England. I had a house mate who decided that it would be a good idea to start a prank war with me. (His first mistake) we traded off hiding each others stuff and playing dumb... I ended the mischief by taking all of his clean underwear soaking it in water and putting it in the BACK of the house freezer. Took him a day or two to notice and noticed it when he was getting ready to go out for the evening. Pure hilarity.
they are pretty sophmoric compared to some of the others on here, and I am sure there are more, but those are my favorites!