Monkey Clawing is when you speedily pull your pants down, shit in your hand, and proceed to chuck your feces at someone. Just like some monkeys do at the zoo, they poo in their hands and then throw it at humans passing by.
Normally done to someone in which you have a strong hatred for. This usually takes place outside, as you wouldn't want to get shit all over the inside of a building.
John: Dude Jill keyed my car, I'm going to Monkey Claw her"
Joe: Hell yeah dude! Let me get the camcorder!"
Mike: AWESOME! JOHN'S GOING TO BUST A MONKEY CLAW!