Paul Crowley

To quote someone or other:

"...such games are amusing when played by those who are funny, and a matter of hiding under the table when played by geeks"

Concealing the fact that there are no rules to MC would seem to me to only encourage the cliqueyness of the game.

The cliqueyness of the game would seem to me to be the primary reason why unfunny geeks would play it.

Therefore, the correct thing to do is to point out there are no rules.