Played by as many people as you want. Deal all the cards out so everyone has an equal number. Dealer flips his/her card and then the person to the left flips their card...if the cards are the same suit or the same numeric value both people have to drink while the next person in the circle counts to their number.
If you finish your drink before the counter gets to your number slam your cup down and they have to drink while you count. Keep going in a circle until all the cards are gone.
Your buzz varies on what cards you're dealt. The first time I played my lowest card was a 6 so I was drunk in a hurry.