Running into a man and dropping your things as a result. Mark Sanchez is prone to assfumbling, but an assfumble can happen on the street. Walking into a man and dropping your
bag or running towards the
line of scrimmage and hitting your offensive lineman in the ass, fumbilng.
Football Example: Mark Sanchez has the ball, he makes contact with his lineman, assfumble!
Patriots have the ball! Patriots have the ball!
Everyday example: Man, I was walking to the store when I ran into a
guy and totally assfumbled my
phone.