A person who is real nasty. So nasty they do anything to anyone. Often sexual in nature. You don't wanna mess wiv these badboys. still they are not to be confused wiv the nastyboys of www.nastyboys.com who are actually rather gay and pornographic.
Chris: Why did you hit that man on the head wiv your sledge hammer and then piss all over his face?
David: Beacuse im a NASTYBOY!!