A beer drinking lifestyle, not a game. When you join Jumanji, you join a group of party-goers who will only drink beer from their non-dominant hand. If a group member sees someone (that can possibly be in Jumanji) drink with their dominant hand, they should yell "Jumanji." When called out that person has to finish that entire beverage on the spot.
Some side rules:
Like I said before it's a lifestyle not a game, you cannot turn it on and off.
There are no "put it on my tab", or "I'll do it laters."
When the can/bottle touches their lips it's fair game.
If you are not in the club you cannot call Jumanji on other people.
If you decide to leave the club for whatever reason you will be branded a huge pussy.
Possible local rule:
Jumanji rebound- If the person you call out for example is left handed and you think he is right handed and he is drinking with his non-dominant hand, he can call you out and tell you to finish your beer.
If you do not follow the rules of Jumanji, you should have never joined the group in the first place.
Wow, Jim is so wasted, "look he's about to drink with his right hand. JUMANJI Jim!" Jim laughs and finishes his beer.