Let's be honest: with the exception of fragile senior citizens and small children, few things are more amusing than watching someone fall down in public.

And when it's a celebrity falling down, even better. 

Sticklers will argue that Justin Bieber, instead of falling down, actually falls through a trap door hole in the clip above. But whatever. That doesn't make it any less funny, especially when you hear the giant painful-sounding thunk. 

And give the guy credit for his improv skills. After clambering back onto the stage he, instead of calling in the medics, announces "Good thing I'm like a cat and landed on my feet."