A very unattractive, creepy guy at bar, who lurks, watches, and looks for women to hit on. He is also the unattractive, creepy guy on the dance floor who will attempt to dance with you multiple times and never get the hint that you don't want to.
Genereally means bastard, but not in the literal term. Just an annoying person who you don't like or who has done something stupidly irritating. Most comonly known from Mean Girls.