This game requires patience and subtlety. The first player makes a statement, the second player must disagree by saying 'No it isn't' or words to that affect. The first player says 'Yes it is' and this continues until the parents intervene to shut the pair of them up. Then the game begins properly.

The aim is to wait as long as possible, then say either 'Is not' or 'Is so' depending on which side you are playing. This must be said so quietly that the parents don't hear you, but the other player does. The winner is the person to get the last word.