A person who tends to push very hard to get the best end of the deal. Or, a person who is very high maintinence once a deal is made.
"I told this guy the car/TV/crack rock was $200 and he kept on trying to talk me down for 30 minutes, what a "nut cutter."
"The hitman agreed he would cap my cheating boyfriend for $3000 and a gas card, now he wants to haggle over the AMOUNT of the gas card. What a "nut cutter!"