A lot of people say that women are poor judges of size. Yeah, maybe when it comes to giving actual numerical measurements. But I've been thinking this for a while:
If you had something crammed up inside your body, wouldn't you remember how big it was? They know! At least by feel. Trying to translate that into a measurement, well, that's another story....unless a chick wants to carry a ruler around with her which would be really fuckin' tacky.
Are you gonna carry a suitcase full of different sized dildos, and make them choose the closest one?