1. Someone who goes to the gym and only works out his biceps, triceps, delts.
2. Sometimes its a person that only works out his portions of his upper body. For example. His work out may consist of doing curls, tricep extentions and bench pressing; yet he does not squat, deadlift, dip, etc.
Look at Tony. He's such a curl jockey. I never see that guy in the cage doing squats or deadlifts for that matter.