How to play

Players sit in a rough approximation to a circle. Whoever starts will pick a starting direction around the circle by quothing "To my left.." or "To my right.." and then start play.

Play is made by counting out loud upwards towards 21. The first player will start at 1 and then each player will continue from where the last player left off until 21 is reached. When it is their turn each player has 3 options
Count 1 number - In this case play will pass to the next player in the circle in the current direction of play.
Count 2 numbers - In this case play reverses direction and play passes to the next player in the opposite direction. play then continues in the new direction.
Count 3 numbers - In this case play continues in the current direction of play but skips one person.

Players must drink if they
hesitate when it is their turn
Count when it is not their turn
generally screw up
reach 21 on their turn

A new round of play then starts again at 1 with the person who screwed up. obviously the object of the game is to force others to say 21 while avoiding it yourself. ( TIP: its fun if you gang up on someone )

But it doesnt end there! If someone reaches 21, then after they drink they have the privilege of replacing one of the numbers with another word. For example "4 is now Aardvark". For all subsequent rounds players must remember to replace the number '4' with 'Aardvark' or else they will have 'screwed up' and must drink. (This continues until enough numbers have been replaced for everyone to agree it has become too confusing at which time they may wipe the slate and return everything to their original numbers.)

TIP: When replacing words try to build humourous phrases using subsequent numbers
TIP: If you want to be really nasty try replacing a number with another number eg " 6 is now Seven "

So after a few rounds, a round of 21's might sound something like this...
"To my left..1,2"
" 3, Aardvark, 5"
" 7 "
" 8 .. oh shit"