Rules of the game!

Nobody ever read the rules of the game

The rule page was torn out but we thought we didn't need it
Common sense and honesty should take care of things
We'll define the rules as we go along
But what happens when we can't agree on the rules?
Do we quit the game or act like we're okay - perhaps compromise?
Or do we pick another game and decide on the rules from the start?
Who defines what's fair? Is there ever a final say?