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. Some people masturbate by using machines that simulate intercourse. It is also followed by dedicated industry publications and trade groups as well as the mainstream press, private organizations , government agencies, and political organizations. These are often fake. Following the introduction of the Motion Picture Association of America film rating system, independent videos porno gay animation producers attempted to establish an alternative to mainstream animation. A 2009 study found that heterosexual male fat admirers preferred females that were clinically overweight and rated both overweight and obese women more positively than slighter individuals. For some people, non-penetrative sex is the primary sexual activity of choice above all others. Irrespective of the legal or social view of pornography, it has been used in a number of contexts. The consensual submission of the submissive is sometimes demonstrated to others by symbols indicating his/her belonging to the dominant, such as wearing a collar, special tattoos, piercings, a very short haircut or a bald head. Rainbow parties were covered on The Oprah Winfrey Show in 2003, and became the subject of a juvenile novel called Rainbow Party. The term pearl necklace is used by some because the drops of semen deposited by the milf xxx man resemble a necklace of translucent white pearls. Internationally, hentai is a catch-all term to describe anime hentai a genre of anime and manga pornography. Positions can also be chosen specifically for added effects such as increased humiliation, elevation and suspension. Women who perform in lesbian pornography often do not consider themselves lesbian or bisexual. Breast fetishism is a paraphilic sexual interest focused on female breasts . John Stagliano is considered to have started the gonzo pornography genre with his Buttman series of films. A related term used in the genre is the term cougar, which implies an older woman as predator.