The majority of my senior class pitched in money and we went to Costco (at the time Price Club) and bought 2 and a half pallets of Jello. We then proceeded to dump all of it into the Olympic sized pool, and the following morning the pool was full of Jello. The principal was not happy about that, but then a few days later not to be outdone, a few idiots decided to hotwire the school's backhoe and drive it into the deepend of the pool. Not only was the pool half full because of our stunt, but when they drove the tractor in the bucket hit the bottom and cracked the pool. By the next morning all of the water had drained out of the crack. These people were caught though because the jackass that drove the backhoe was too drunk and couldn't jump clear of it when it hit the pool and Monday morning rumors started to fly because he couldn't explain to his parents or the ER staff how he broke 4 ribs, and his right arm just swimming. A few of his friends parents also had major discussions with their kids and managed to get the truth. Apparently he hit the edge of the pool because he couldn't clear the seat when it started over the edge.
Nobody got caught with our stunt because the money was passed around to about thirty people and nobody was really sure who went to get the jello, plus I had my two friends help me and they didn't go to our school because they were kicked out and sent to a different school. So, who better to pull off a prank with than two guys that wanted to get back at the school anyway...................