1. A guy who drinks lots and falls over every available free moment.
2. The evil monster that visits you when you have been on a bender
and steals all your money, sends bizarre text messages and offensive e-mails to all your friends, makes all your clothes smell funny, hides your underwear, messes up your house, and then shits in your mouth before leaving.
Also wipes all your memory of the previous night.
By either definition, he's a cunt
and you spend all your time apologising for him.
1. I have never seen Rob sober, the guy's a complete Beer Monster.
2. I need to go into town, the Beer Monster stole all my money, <vomits>, maybe later...