A proper name given to a man who continuously betrays the trust of his significant other, and excels at it. King Popalop not only looks to cheat, he makes cheating an art, leading others to ask: "Does he know how to do anything besides cheat on his wife/girlfriend?"
Setting - a bar
Bob: Where did Bill go?
Fred: I don't know he was just talking to some girl by the bar.
Bob: I wonder where he is. I'll call his cell phone.
Bill's cell phone: Ring. Ring.
Bill: Yo Bob, whats goos?
Bob: You tell me whats goos. Where you at?
Bill: In this girl's crib right now, with eleven of her girlfriends.
Bob: Yo you are King Popalop right now!