Someone who fails epically at a simple task, or is just a complete douche bag. Derived from football players that fling their chin strap off after an epic fail.
Joe: HAHAHA! Jeremy, Did you see Bob try to but that hottie at the bar a martini then spill it all over her...
During the performance of oral sex on a female, a bearded male will place his chin between the vaginal lips and shakes his head back and forth rapidly and lightly to induce a pleasurable experience for the female.