In Japanese, the term describes any type of perverse or bizarre sexual desire or act; it does not represent a genre of work. The videos gays 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. 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. Rainbow parties were covered on The Oprah Winfrey Show in 2003, and became the subject of a juvenile novel called Rainbow Party. Barebacking usually refers to a conscious and deliberate choice to forgo condoms. Diaper fetishism, nappy fetishism or diaperism, is a sexual fetish in which a person feels a desire to wear or use diapers. The activity is done by itself or as a part of or prelude to other activities which many times involve sex. Among swinging couples, one of the two partners is often the driving force and the other is more passive-supportive of the addition of additional sex parties. Solo horny milfs performances in gay pornography have been described in 1985 as either or both active and/or passive , whereas female solo performances are said to be exclusively passive . 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. A study of 164 males in Finland from two SM clubs found that 18.2% had engaged in coprophilia; 3% as a sadist, 6.1% as a masochist, and 9.1% as both. 18% of heterosexuals and 17% of homosexuals hentai videos in the study pool had tried coprophilia, showing no statistically significant difference between heterosexuals and homosexuals.