If your kids are arguing over anything, you just say rock, paper, scissors and they're off!! and the loser loses without a mutter.
I've seen 12 kids play rock, paper, scissors make a decision so efficiently it's unbelievable. Here are some of my boys playing the game "pogs" on their break. (Anthony and I vaguely remember this game as "pogs")...
Rock, paper, scissors for all!!
And for the crude adults around - you can simply play muff, cock and bumhole - taken from the AMAZING British television show Nathan Barley - you can watch it all on youtube and it is hilarious.