This term may also refer to a near-
mythical sex act between two
women. It relies on the fact that when a woman is
sexually aroused, her
nipples become firm and (for some women) substantially larger (
men's do as well, but working from a smaller
baseline).
Effectively, one woman uses her nipple -- steadied by her hands -- as an organ for
penetrating the other's
vagina. Obviously deep penetration is going to be impossible here, but in addition to surface
stimulation, the woman doing the penetration is in an excellent position to
bring her partner off with her hands. And, unlike the male tittyfuck, this stimulates the more sensitive areas of the
breast, opening the possibility that both individuals will
enjoy themselves.
This act is certainly performed more commonly by
porn lesbians than by any real women. In pornography, any contact between an erect nipple and a vagina results in instant multiple
orgasms (followed by an unstoppable urge to find a funny-looking guy and drag him in for a night of
cum-drenched
bisexual bliss).