Common positions include lying on back or face down, sitting, squatting, kneeling or standing. Being forced to wear diapers as a form of humiliation is sometimes a behavior encountered in sexual masochism. Rainbow parties were covered on The Oprah Winfrey Show in 2003, and became the subject of a juvenile novel called Rainbow Party. Some straight actors have started acting in gay porn only to be accused of being gay while others first step was to strictly do solo scenes. While anal sex is commonly associated with male homosexuality, research shows that not all gay males engage in anal sex and that it is not uncommon in heterosexual relationships. Reality and voyeur pornography, animated videos, and hot gay sex legally prohibited acts also influence the classification of pornography. Exhibitionism: Becoming noticeably desperate or wetting oneself momsex with the express purpose of being seen by strangers. 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. Lolita pornography caters to ephebophiles. Bestiality is illegal in many countries. A related term used in the genre is the term cougar, which implies an older woman as predator. It is typically animated pornography, as the legal age to be featured in a pornographic film in Japan is 18. By comparison, gonzo pornography puts the camera right into the action, often with one or more of the participants both filming hentai movies and performing sexual acts, without the usual separation between camera and performers seen in conventional porn and cinema. Mutual masturbation, mutual manual stimulation of the genitals between partners, can be a substitute for sexual penetration. Felching is a sexual practice involving the act of orally sucking semen out of the vagina or anus of one partner.