Armback
An armback is when a kook surfer thinks they are doing a trick, but in reality they are just moving their arms behind them.
Taylor: "Dude, did you see me do that fatty cutback?!?!"
Johnny: "Shut up fag, that was an armback. You suck at surfing "
Johnny: "Shut up fag, that was an armback. You suck at surfing "