A term used in weightlifting. An amount of weight that can be lifted by your average Joe. The term also relates to the attitude of the lifter, who believes himself to be strong when, in actual fact, he's not. This makes him a chump, not the weight on the bar. Typical weight of chump weight in e.g. the bench press: 220 lbs or 100kg.
Joe: I can bench 220! Schmoe: Don't you know that's chump weight?