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 masturbate only using pressure applied to the clitoris without direct contact, for example by pressing the palm or ball of the hand against underwear or other clothing. As a form of non-penetrative sex, it can be done for its own enjoyment or as foreplay. Mammary intercourse has sometimes been considered a perversion. Snowballing or snowdropping is the human sexual practice in which one person takes someone else semen into his or her mouth and then passes it to the mouth of the other, usually through kissing. Reality and milf fuck voyeur pornography, animated videos, and legally prohibited acts also influence the classification of pornography. Biological anthropologist Helen B. Rimjob pornography centers around anilingus. The neologism pegging was popularized when it became the winning entry in a contest in Dan Savage Savage Love sex advice column, held after an observation was made that there was no common name for the act. The naked appearance of actress Demi Moore in the advanced stage of pregnancy on the cover of Vanity Fair magazine in 1991 marked the beginning of a period which has since seen pregnancy presented by celebrities as a glamorous state of living, while also creating a market for photographers to produce images of pregnant mothers, and for fashion stylists to introduce pregnancy styling to their business. The Girls Gone Wild series is one example. Cartoon pornography is the portrayal of illustrated or animated fictional characters anime hentai in erotic or sexual situations. Typically features adult, masculine men with varying degrees of muscle, body fat, and body hair, akin to beefcakes, or bears. Special forms include erotic roleplay like ageplay, in which a difference in age, either real or enacted, formulates the background; or petplay. Instead, all five fingers are kept straight and held as close together as possible , then slowly inserted hot gay sex into a well lubricated vagina or rectum.