Stumping is a fun way to trip someone when they are running directly behind you. It can be used as a practical escape method or a as a hilarious prank.
Right as your pursuer is directly behind you, hit the brakes and crouch down, much like the fetal position. Not being able to dodge this new obstacle, the unfortunate pursuer, still running at full speed, runs into you with his legs and finds himself a whole load of bad luck usually in the form of flying, faceplanting, public humiliation, or other injuries.