Math.

Yesterday Cute Coworker and I mathematically worked out that in any group with equal numbers of heterosexual men and women, both sexes must have the same average number of sexual partners.

(This may be incredibly obvious to those fancy educated members of the audience who passed math classes. Hush, it took us like two hours and five scribble-covered pages to work this out. Math is hard, guys.)

I realize that the median number can be different, and a handful of super-prolific bedhoppers can give you a skewed image of the group as a whole, but still, this seems like a blow to both the old "men should be studs, but women shouldn't be sluts" double standard, and its whinier more recent cousin "women can get laid and men can't."