Slob Air - A frontside mute where you tweak so that the tops of your feet are crunched onto the board. You look all twisted up on like you would be if you were kneeling sideways on the ground, you slob.
Invented by Blair Watson in 1979. Aka layback air. Documented until 1982 in Thrasher Magazine (the move was named by Thrasher photographer Mörizen Föche, aka Mofo, who took the shot). From Wikipedia.