The number rolled corresponds to the number of the tankard in the line. If it's empty, the roller fills it as much as he wants and play continues with another roller. If it contains beer, the roller must drink it all up and roll again. This confusing game was created by some nobles so they would have a drinking game that few low-lifes could learn. Unfortunately, they have trouble with the game.
Thief takes a bit to catch onto, but once understood, it is quite competitive game.
The game requires people, beer, and dice. A player arbitrarily goes first by rolling the dice. The eventual loser has to drink double the standard drinking quantity being used for the game. Each subsequent thief in that round will double the required drink for loser. This will be easily understood later.