A girl who has no ass, no boobs, or neither. Named after the "karate chop" motion, a straight-down chop that signifies the flatness of the body. Not necessarily negative or positive in connotation, simply a description. Can be used as a motion.
"She's cute, but she's a karate chop."
Ed: I saw this girl at the mall wearing a haltertop.
Sam: How big where her boobs?
Ed: *karate chops*