Playing the Numbers

Conversation in van yesterday...

Andrew: I didn't have a good lunch today. My friends were gone so I
was the only boy at table one. The girls just argued with each other
the whole time.
Ryan: Girls always argue. And they can't play together in odd numbers.
If two girls are playing and another one asks if she can play, they
always say no. Boys can play in all kinds of numbers - even or odd.
Like 3 or 7 or 9.
Andrew: Guess we are lucky we are all boys since there are three of us!