The result of when you've hunched forward while playing video games for an extended period. Rolls of flesh on your abdominal region create horizontal lines of skin irritation. When you stand up, shirtless, they appear quite clearly. Resembling a sort of developed ab muscle set. It can occur in anybody who isn't completely anorexic, not just fat people. They're temporary, the skin irritate goes away after a short while.
"He has been playing Halo for hours, check out those gamer abs!"