The best prank that I've ever seen was done last summer by the counselors to the oldest girls in camp. It's kinda tradition that this happens. Anyway, some counselors gathered up all the alarm clocks they could and they set them all about 30-60 min apart starting at around 1am and lasting until like 6am. They strategically placed them throughout the cabin of the oldest girls. I mean these things were everywhere, like in the rafters above, in their bags, under beds, all over. It was so great, cause they had no idea where they were coming from and couldn't stop them from going off. This was HYSTERICAL!!!
As you know with every prank, there is one in return. So the next morning the girls put all the kayaks in camp up on the rafters in the dining hall. That wasn't as funny though.