when one proceeds to get blackout drunk for 12 consecutive days in a row
in order to complete the Drinkers Dozen you need go to the bar 12 nights in a row and get smashed as fuck, side effects include: pissing the bed, projectile vomiting, tarnished bank account, and potentially some STDs.
Eleven, or one less than a dozen. The drinker is likely to misplace, break, miscount, or consume one from the fill the full dozen.
Jeff showed up with a drinker's dozen of beer, having drank one on his way. They decided the first team to a drinker's dozen(11) wins.