Barton,
While not as, um, accomplished as Dick and Tracy, pet and I have been working diligently on this, which usually results in sex immediately following. Absolutely no stretchage that I can tell. pet works on her interior muscles as well, and the end result is a deliciously good grip on things. My things, that is, and while I don't know if the kegel work does the trick or not, the trick is certainly done.