not really a prank but a few good stories. When I was like 12, I was on vacation with my family down at the shore in Maryland. My dad, uncle, and myself went out deep sea fishing on one of those party boats. They had a little pool contest where you could put like 5 bucks in, and have your largest fish weighed, and the person who caught the largest fish would win all the money in the pool. Well, a few hours later, my dad pulled up a giant flounder, and we kept it... Back on shore, we were about the 2nd to last ones to get our fish weighed. They weighed the flounder, and the guy said it was the heaviest fish they weighed all day. Well, just then some idiot guy walks up, and pulls a huge sea bass out of his cooler. He weighed it, but it was about a pound and a half lighter than our flounder. Frustrated, he had the guy with the scale weigh it about 10 different ways, with the same results.. I finally said, in front of the crowd that had formed, "you lost, ok?? get it through your head!!" The look on this moron's face from being completely owned by some 12 year old young punk was priceless