A random itch that is caused by stress while playing a video game. This usually happens while playing a game where you can't take your hand off of the controller.
I was on the final level doing some heavy button mashing then I got gamers itch on my elbow.
The itch that happens to come out of no where when you playing an intense video game. usually appears when playing guitar hero, rockband and halo. causes you to have to either pause the game and scratch or quickly scratch during game play, most of the time causing a mistake to be made in the game.
gamer 1: "dude you just screwed up the mission"
gamer 2: "well sorry i had a gamers itch"