One person is the dealer.
He/She will deal two cards, face up, with room between each for another card.
The game starts with the person to the dealer's left. The dealer turns over the 1st two cards. The person to the left then bets that the next card will be between the two cards already shown. A bet of between 1 to 4 can be made. This is 1 to 4 shots of beer, alcohol (although using alcohol makes the game end REAL soon!) or chugs of beer. The bet has to be made after the two cards are shown, but before the 3rd card is drawn.
If the person guesses correctly and the card is between the two cards (i.e. 2 cards drawn are the 4 of any suit and the Queen of any suit and the 3rd card is the 8 of any suit), then they win and can tell anyone in the group that they choose to drink the number of drinks that they bet.
If the 3rd card doesn't fall between the other 2 cards (i.e. the 6 of any suit and the 10 of any suit are drawn and the 3rd card is the 4 of any suit) then that person has to drink the # of drinks that they bet.
It can be a fast paced game and the group usually likes to pick on one person.