Vital foundation for the positive outcome of a party, stating that there should at least be one vagina present for every testicle. As a result a party with a good "balls to pussy ratio" provides two females for one male.
"Dude, that party sucked. Seriously, there weren't any chicks at all."
The cock to pussy ratio, or cock:pussy, is a way of measuring the amount of guys in a group versus the amount of girls.
It can then be simplified down so if there were to be a sexual adventure the amount of cocks to pussys would be clear.