So many bones were broken to make this.

The world of extreme sports seems to be mostly about one upping each other. I remember for a while people were trying to do a 900 on a skateboard, which Tony Hawk was able to pull off.

BMXer's have been trying to pull off a quad flip. You'll understand once you see the video how hard that is. They have to launch themselves off quite a steep ramp and start flipping right away. The fourth flip has to be perfect as it's timed to have your wheels hit the other ramp just as you finish the rotation, so balance becomes key.