A person who plays computer games (especially fighting games) with the use of his/her lightning fast reflex of randomly pushing/bashing/smashing and yanking each and every button (including the buttons of the player next to him/her) on the contoller/arcade without any idea what the hell they're doing.
A man who exudes total confidence in all situations. A masher will back down to no man, and often emerges decidedly victorious from any physical confrontation or daring act. As a result of the mashers extreme confidence, a masher is no stranger to having his way with many an attractive woman.