Sometimes Billy absolutely amazes me

Billy the Kid, my office mate, informed me this week that he didn't know his girlfriend's last name. His defense being that in spite of his dating her (in every sense of the world), she wasn't actually his "girlfriend", so it's really no big deal that he didn't know her last name. "Besides", he said, "I think I knew what it was but I forgot". I asked how long he's known the young lady and he answered, "eight years". How is that even possible? I think the only way you can know somebody that long and not know their last name is if they don't have one, like Cher, Prince or Madonna. Somehow, Billy pulls it off though.