What you are doing is gloating when your enemy falls, which Jesus commands us not to do. Some people feel so bad about themselves that they laugh at the fact that someone elses plans didn't work out. This is the oppositie of what we should be doing. It is also stupid if people laugh at someone getting hurt or someone tripping over or smacking into a wall. There is nothing funny about this. People who laugh at that type of stuff are people who don't think about the consequences of particular actions. They don't think that maybe someone could have been hurt.
