Personally I never found it funny or amusing anyways because I'm a buzzkill I guess...but someone did this to me a few years ago and it destroyed a Windows Mobile Phone and an iPod Nano I had in my pockets. Maybe it is my fault for not assuming, but I don't find enjoyment in pushing people in pools.
Me: hey is your phone in any of your pockets?
Friend: *checks* no why?
Me: HAHA FUCKER! *shoves them into pool*