Say goodbye to the contents of your stomach, especially if you have a fear of heights. Or, you know, dying.
This is why all those daredevils who climb tall buildings and start doing loads of gymnastics and parkour are actually really, really mind-bogglingly crazy. 'Sergey Jumping Buddha' was on the edge of the 40th floor of a building in Israel in July and did what all those crazy free-running/parkour Russians do and decided to do a backflip with no safety equipment or anything around him.
And then he bunched the landing and nearly fell off.
We feel like vomiting.