THe exhausation of the use of ones thumb often leading to aggravation of the skin e.g blisters and often a great deal of pain. Hinders performance when competing and is a valid excuse for under performance. (see tennis elbow)
"I only lost that game cos of my playstation thumb you cunt!"
A medical condition first coined with overuse of the Sony Playstation but has continued to be a problem due to the Playstation 2. The thumb button controller design means that after extended play of racing games, the right hand thumb can ache and become numb.
Also see: Dreamcast Finger
I can't play Gran Tourismo any longer, I've got Playstation Thumb.