vaginal depth
The new age unit of measurement for use in interpersonal relations. Until now penis length has been the standard. However vaginal depth is far more useful for both women and men, as it shows who is compatible with whom (every bloke obviously knowing his penis length).
Mick keeps bragging about having a ten inch dick. He's going to find out how useful that is - NOT - when he hears that Emily only has a vaginal depth of 7 inches.