|All players sit in a ring (gender has no effect, there is no contact involved as part of the game). Betting then commences in a fashion similar to limit-poker. One player begins by saying "one". The person on their left may then raise this to "two", may repeat the word "one", or may "pass". If they pass, they sit out for the remainder of this round.
Once everybody in the circle has either said the same number (you may wish to place a limit on the maximum number to extend the game) or passed, the number which was said is drunk. For example, if everyone says "five", everyone who did not pass drinks five sips.
All those who drank then take it in turns to roll a die. The person who rolls the highest number may force a person of their choice to drink 5x the number rolled. Eg, if the rolls are 4,2,2,3, the person who rolled 4 may force somebody to drink 20 sips. They may also divide this amount amongst several people, i.e. 10 to two different people, if desired. People who passed cannot be forced to drink.
Repeat as desired.
You'll find that as the game progresses, people will raise more often, meaning that the effect truly is a downward spiral!