Pulling a prank is one of the biggest achievements a human being have (no other interpretations here). No amount of gold medals can give the pleasure that comes from trolling another person successfully.
Now, imagine that you are trying to pull a prank on somebody else, and it goes all too well for a while. And now, imagine that the other person realizes that s/he is being fooled. Now imagine him/her beating you back in your own game. Not only does your spectacular plan fail, but you get trolled too! Heartbreaking, I must say.
Check out this video by Kidu Videos for some laughter attack. Be careful about your diaphragm though, mine almost broke laughing!