When playing a competitive game and the individual that is gradually losing scratches his/her head(Scalp) or facial features extremely fast due to the frustration of not being able to achieve victory. Hence... The gamer scratch AKA- The frustrated gamer.
Its a tie in super smash brothers 64 and link boomerangs and bombs the fuck out of pikabitch to achieve victory. Pikabitch fails to dodge several of links projectiles therefore initiating the "gamer scratch".