If you are walking somewhere with your friends, and you decide that you want to make them laugh, it often works to pretend to trip and fall. This works particularly well when you are going up stairs. I just make myself miss a stair and fall down. Everyone usually starts laughing. However, the major problem with this laugh-inducing act, is that whenever I do it, it then becomes impossible to prove to my friends that I did it on purpose. They are all laughing at me, and I'm like..."I did that on purpose you know."...and they are like, "yeah right." Then it continues back and forth like that, and I can't prove my case. This then attacks my pride, and I end up irritated. So, in summary, tripping on purpose will make your friends laugh, but will leave you pissed off.