hmmm..... You might have to wait another 16 years to do this one, but its SO worth it. Last year there was this AP Stat teacher that failed more than half of his class, and they really weren't that happy about going to summer/twilight school. So this was around June of last year after finals, and especially when the cidadas were out. They were EVERYWHERE around our 90+ year old school building. EVERYWHERE. So the kids I know that were in this class collected two trash bags worth of live cicadas and the shells and put them in his class after he had left for the day. There were cicadas EVERYWHERE in his room. They ate up all of his plants and were all over his desks. Not only was the sound deafening, but it took A LOT of work for him to get them all out. It was something I will never forget.
Another prank from my high-school career (which is pretty much over.): A teacher failed a kid, and he put only about three tablespoons of milk (that's really all it takes) in his car under his seat. The teacher had no idea where the smell was coming from, and he never figured out. All he really had to do was take out the mat and wash it, but he didn't know that. Now his car has COMPLETELY new interior.
Moral of the story: Teachers, beware of the students you have just failed. ESPECIALLY the creative ones.