Bukkake pornography involves a performer, usually female, onto whom several men or women ejaculate, usually on the face. Diaper fetishism, nappy fetishism or diaperism, is a sexual fetish in which a person feels a desire to wear or use diapers. Reality and voyeur pornography, hentai movies animated videos, and legally prohibited acts also influence the classification of pornography. Foot fetishism has been defined as a pronounced sexual interest in the feet or footwear. John Stagliano is considered to have started the gonzo pornography genre with his Buttman series of films. 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. Clothed male, naked female is one-sided female gay cock nudity in which one or more females are nude while one or more men are clothed. This type of pornography is almost exclusively hentai, as true hermaphroditic humans are not fertile and are not usually found in nature. Specific sex acts Anal Anal pornography features anal penetration with a penis, dildo, other objects, or some combination of them. Women who perform in lesbian pornography often do not consider themselves lesbian or bisexual. Tentacle erotica can be consensual, but frequently contains elements of non-consensual sex. Women oriented pornography is sometimes nude milfs referred to as sex positive pornography. The most common male masturbation technique is simply to hold the penis with a loose fist and then to move the hand up and down the shaft. There has been an increase in discussion and portrayal of masturbation in art, popular music, television, films, and literature. For instance, Amateur Allure has a trademark shot where the sexually performing cameraman circles a handycam around the sexually performing model head.