The stalefish is a skateboarding/snowboarding move that is a relatively simple concept, but still has a great name and a decent story to go with it.
When a talentless hack named Tony Hawk invented this trick at a Swedish skate camp in the mid-80's, he had just had some canned fish. When he called the mess "stale fish", a skater thought he was naming his new trick. Oh, how miscommunication changes the world.
The stalefish grab is simple enough. While in the air, either off of a launch ramp or vert, you grab the heelside of your board with your following hand, in-between your feet. For extra style points*, arch your back and really reach back there for it.
If that description isn't clear enough, go play some Tony Hawk's Pro Skater and press down-left and the grab button while in the air. Your player of choice will then perform a stalefish air, rendered in wonderful 3d.
* you will not actually receive more points for this unless you are in a contest or are playing a video game. It's just an expression.