The female
equivalent of a boner.
verb: grip
Female anatomy allows for a state of heightened pleasure, wherein when a female is
sufficiently turned on, the opening of her vagina will contract, along with the clenching of the main pelvic muscles and other auxiliary muscles, thus allowing her vaginal tract to 'grip' firmly onto the inserted male penis. This 'grip' is the male equivalent of a boner, without which she will not be able to have her release.
This grip may happen naturally, where her state of being turned on is high enough for it to happen; alternately she may induce this state by clenching her all pelvic muscles
simultaneously, for a period of a minute or more, while 'thrusting' happens.