Play pool as normal, only for every red ball potted, down a shot of Red, for every yellow a Gold, etc. The White drink should be refilled as required. Winner may drink the Black or force his opponent to do so.
Rules on fouls, penalties etc should be negotiated beforehand - standby beers are often a good idea, to drink as a forfeit or while waiting your turn. Any spirit drink may be substituted to match tastes/different sets of balls etc. The game can be played with pints of beer, but is seldom completed... Go check out his homepage at http://www.geocities.com/Hollywood/Set/8757/