Everyone sits in a circle and a leader is choosen (the one who knows the games outcome) It can only be played if at least one person doesn't know the game. Take that one person and have them sitting to the leader's side.
Explain that the games rules are this:
The beer will be heated up from the bottom with a lighter by the leader, then the leader will do something funny to the person at their side (the one who doesnt know the game), they will have to pass that gesture on to the next person until it makes a full circle. No laughing is permitted! If anyone is caught laughing they will have to drink the "flamming natty" which is being heated up as the game is going on.
The key to this is that the leader will heat up the beer from the bottom of the can, as the leader goes to touch the person at their side they will causually (don't get seen!) wipe their finger on the underside of the can. The fire will produce a black soot which will be wipped off on the persons face.
If people laugh you must improrvise and threaten them but never carry it out till the persons face is covered and they are the only one not laughing!!!!!