Preggo pornography features pregnant performers and may include erotic lactation as a fetish. It contains graphic sexual activity and visible penetration. Lying face down one may use the hands, one may straddle a pillow, the corner or edge of the bed, a partner leg or some scrunched-up clothing and hump the vulva and clitoris against it. They may be noted for using risqué themes, graphic violence, sexuality or black comedy in a manner that is unsuitable for younger audiences. Internationally, hentai is a catch-all term to describe a genre of anime and manga pornography. The term is typically used by the cinematographer within the narrative framework of a pornographic film, and since the 1970s has become a leitmotif of the hardcore genre. There are various subcultures under this umbrella term and distinct difference between these subcultures. These actors often play the top roles but this is not always the case, such as with Kristen Bjorn and some Bel Ami models. New York photographer Irving Klaw also published illustrated adventure/bondage serials by fetish artists Eric Stanton, Gene Bilbrew, Adolfo Ruiz and others. Evolutionary psychologists hentai movies suggest that rounded buttocks may have horny milfs evolved to be desirable trait because they provide a gay twink porn visual indication of the woman youth and fertility. People may experience pleasure from anal sex by stimulation of the anal nerve endings, and orgasm may be achieved through anal penetration – by indirect stimulation of the prostate in men, indirect clitoral/G-spot stimulation in women, and associated sensory nerves . It is typically animated pornography, as the legal age to be featured in a pornographic film in Japan is 18. Older names for a pornographic film include stag film, and blue movie. Many fantasies include the macrophile shrinking before a normal sized woman or keeping his or her normal height while the partner grows in size. Perhaps following the example set by gay pornography, they have become a popular subgenre within heterosexual pornography since the turn of the century, featuring both vaginal and anal ejaculations.