Once insertion is complete, the fingers are either clenched into a fist or kept straight. Interactive pornography, available in CD-ROM and DVD format, allows the viewer to select the particular acts performed at any one time, sometimes with the camera providing a first person view. The glans itself may widen and lengthen as the stimulation continues, becoming slightly darker in colour, while the gliding action of the foreskin reduces friction. Reality and voyeur pornography, animated videos, and legally prohibited acts also influence the classification of pornography. Lolita pornography features women who are 18 years old or slightly older, who pretend to be underage teen girls. Mutual masturbation, mutual hentai sex manual stimulation of the genitals between partners, can be a substitute for sexual penetration. Some men also enjoy anal stimulation, with fingers or otherwise, without any prostate stimulation. The term combines elements of the Freudian psychoanalytic fetish and the Marxist commodity fetish, and is used in the context of British, Spanish and French colonialism and imperialism and their aftereffects. Sexual orientation Pornography features an increasing variety of combinations of actors by their sexual orientation such as lesbian, gay, bisexual, and transsexuals in addition to traditional heterosexual roles. It is also followed by dedicated industry publications and trade groups as well as the mainstream press, private organizations , government agencies, and political organizations. Because the viewing of such films carried a social stigma, they were viewed at brothels, adult movie theaters, stag parties, at home, in private clubs and also at night videos porno gay cinemas. A pornographic work is characterized as hardcore if it has any hardcore content, no matter how small. Many cultures describe pain as an aphrodisiac. Femdom features BDSM scenes in which the dominant partner is female. The name was coined from the title of the controversial book. It is used, for example, at naked milf fertility clinics to stimulate sperm donors.