Before the game starts, the boot must be filled with three beers. Also, a punishment must be thought of for the loser. Something humiliating, but not mean. For example, once the loser had to go give someone who wasn't playing a good kiss for at least a few seconds. This one was really popular, everyone loved it.
All players sit around a table and someone starts by taking a drink from the boot.
It doesn't have to be as much as you can drink. It can be whatever you want. Then the boot is passed around clockwise. If you pass the boot and the person you pass to finishes the boot, you lose. Then you have to do whatever punishment was decided before the game.