Pantyhose/Tights/Stockings pornography involves women or men dressed in pantyhose, tights, or stockings. Pegging films include Strap It On , Babes Balling Boys , Strap Attack, Strap-on Sirenz, Strap-on Chicks, Boss Bitches , various movies produced by LEDA Studios, and San Francisco-based Men In Pain. Some people masturbate by using machines that simulate intercourse. Men with Women, Women with Men Heterosexual or traditional porn accounts for the majority of produced film and video content in the industry. Following World War II, during a period of social repression when governments actively persecuted homosexuals, women developed networks to socialize with and educate each other. Yaoi male homosexual hentai designed to appeal to women and men. Contrary to the other two types, B/D does not define the Tops and Bottoms itself, and is used to describe the general activities with either partner being the receiver and the giver. Some men enjoy masturbating during pegging. A pornographic work is characterized as hardcore if it has any horny milfs hardcore content. Behind the Green Door was one of the first pornographic films to feature sex between a white actress with a black actor . Sadism describes sexual pleasure derived by inflicting pain, degradation, humiliation on another person or causing another person to suffer. Today, pornographic films can be sold or rented on DVD, shown through Internet and special channels and pay-per-view on cable and satellite, and in adult theaters. These include gently sucking and tugging on the scrotum and use of lips to ensure minimal contact with their teeth. Point of view pornography is adult entertainment filmed to look as if the watcher were experiencing the sex act themselves. Such documents have not been recognized as being legally binding, nor are they intended to be. Upskirt and Downblouse pornography features staged filming up women skirts or down their blouses while in public. Softcore hentai movies pornography that does not contain ejaculation sequences is produced both to respond to a demand by some consumers for less-explicit pornographic material, and gay sex video to comply with government regulations or cable company rules that may disallow depictions of ejaculation.