The basic rules are: (1) No-one can point at anything or anyone. A good substitution for this is pointing an elbow at whatever. (2) First names can't be said of anyone in the room. Nick-names are a good replacement UNLESS their nickname involves their first name (ie. Someone called Bob and nicknamed Big Bob is not allowed) (3) The word scull can't be used. This works well when everyone yells out "You stuffed up! You have to have a scull!", and finally (4) No swear words allowed. A half a glass is a reasonable drink. Especially when someone points at someone and says "You fucked up Kris! You have to scull!" That's four drinks.