Throughout history, women have not had the same freedom or independence to pursue homosexual relationships as men, but neither have they met the same harsh punishment as homosexual men in some societies. Being forced to wear diapers as a form of humiliation is sometimes a behavior encountered in sexual masochism. Following the introduction of the Motion Picture Association of America film rating system, independent animation producers attempted to establish an alternative to mainstream animation. Most bisexual porn is made by small production companies rather than the major studios. The name was coined from momporn the title of the controversial book. Sexual relations between women have been illustrated as well as narrated, but much of the written material from the early modern period has been destroyed. New York photographer Irving Klaw also published illustrated adventure/bondage serials by fetish artists Eric Stanton, Gene Bilbrew, Adolfo Ruiz and others. For some people, non-penetrative sex is the primary sexual activity of choice above all others. The industry generally refers to such films as adult films, which is part of adult entertainment. A study of the condom usage habits of New Zealand sex workers said that they offered various safe sex alternatives to vaginal sex to clients who refused hentai porn to wear a condom. The full-weight body-pressure, moisture, sex hot gay sex odors and darkness can be perceived as powerful sexual attractions or compulsions. Lesbian pornography typically features a wider range of appearances and body types than is typical of mainstream pornography. Women oriented pornography is sometimes referred to as sex positive pornography. The term pearl necklace is used by some because the drops of semen deposited by the man resemble a necklace of translucent white pearls. Urolagnia is a form of salirophilia in which sexual excitement is associated with the sight or thought of urine or urination. Point of view pornography is adult entertainment filmed to look as if the watcher were experiencing the sex act themselves.