adj: Used to describe a nerd or nerd-like person who is muscular, really strong, or can fight really well(see diesel). Can also be used to describe business men who hit the gym way too much and like to wear shirts and ties so tight that you can see their muscle coming through. Taken from the obvious "Superman" movies, cartoons and series.
Bully #1: "Damn dude - what happened to your eye?"
Bully #2: "I tried to jack this nerd for his lunch money - i didn't realize he was such a clark kent."