A prank to play on an unsuspecting male friend. When they least expect it, you silently approach them from behind, and thrust your entire arm through their legs and reach up towards their face, thus cradling their junk with your bicep. At the same time, you must yell "Scorpion!", and watch as they freak out.
I gave Josh the Scorpion, and he totally wigged out and jumped 3 feet in the air.