The unit of measure for how worn out a woman's vagina is which takes into account such factors as the
cumulative number of thrusts from penises into her vagina, the size of each penis, how often she uses a dildo, the size of the dildo, how many babies she's had, etc...
Cock mileage is the unit of measure for the comprehensive wear that has been imposed on a woman's vagina and an indicator of how pleasurable sex with her will be.
Men with larger penises will usually be able to tolerate women with higher
cock mileage and will usually
rack up cock mileage on a woman faster than a more modestly equipped man.
Friend A) Dude, I bet Sarah's vag feels nicer than
Terry's. She's only had a couple boyfriends, so I bet it's still pretty nice and tight.
Friend B) Naw, man. I know Terry's kind of a slut, but she usually goes for guys with low self-esteem stemming from their inadequate penises. Sarah's definitely got higher cock mileage. She fucked her last boyfriend at least
twice daily, and that guy had a
phallusaurus rex.