For an unfortunate grappler caught in a precarious situation, this simple hand motion can be the difference between consciousness/unconsciousness or having a functioning limb/not having a functioning limb.
Sometimes, a fighter caught in a submission wisely taps out before damage is done, signaling "mercy" to the referee.
Well, begin the slideshow to see what happens when a fighter chooses not to tap.
P.S. Be sure to click the links in the slides!