This guy walking down a flight of stairs bit it, but he played it so well that we can't even laugh at him.

The guy appears to miss a step and then proceeds to roll down a few more steps, but he gets up and acts like he doesn't miss a step.

He continues on his way, while on his phone, and acts like nothing happened. Lesson here, keep your head up while walking down a flight of stairs and put the phone away. 

Luckily this guy was injured here, however I'm sure his ego was a little bruised once he learned of this video.