A bastardisation of 'Must-be'. A musbee is a drink, usually
alcoholic, that an unwitting person has left unattended in a pub or club. Naturally the unguarded beverage becomes fair game to anyone willing to drink it, as it would be a crying shame for good booze to go to waste. The cheapest way to get drunk on a night out, very popular amongst piss
poor students and alcoholics. WARNING take a musbee at your own peril, if the snatch is poorly timed you
may be confronted by the musbee's original owner, who
may take exception to you nicking his drink.