Term medically used to describe any interior tissue as it protrudes from an orfice on (but not limited to) the human body. Includes rectal tissue as well as vaginal tissue. Extreme cases of prolapse can include complete vaginal expulsion where the entire interior vault of the vagina falls or pushes inside out through the vaginal opening, causing both the cervix and/or uterus to bulge or hang outside of the female body.
All though it is a serious medical condition brought on by age and/or excessive childbirth, prolapse has gained entertainment value in the adult film and photo industry where women with loose vaginas are fisted and stretched open and often coached to flex or 'push' (force) their cervix or entire vagina inside out for the camera.
Though prolapse in adult film was originally seen as obscene or accidental in recent years it has become an increasingly popular act combined with internal ejaculation and extreme penetrations. Models with loose or prolapse-able vaginas are hired for the sole purpose of showcasing their abilities on camera. Sometimes to shocking and disturbing results.
Medical side effects include the inability to retain urine, feces as well as the inability to contain internal (vaginal or rectal) tissue inside the body during intercourse.
Women who repeatedly force the prolapse of their vagina increase the likelyhood of being unable to keep the insides of their vaginas from bulging out or in some cases hanging between their legs as the connective tissues and tendons can be strained and even broken. In these situations surgery to correct the prolapse is required, otherwise bacteria may infect the exposed reproductive organs (cervix, uterus) as they will no longer be protected inside the female body.
Kerri's pussy is so used she can prolapse it completely.
I saw this one video where a chick did a prolapse so big her entire pussy turned inside out.