Clothed male, naked female is one-sided female nudity in which one or more females are nude while one or more men are clothed. Such documents have not been recognized as being legally binding, nor are they intended to be. Female masturbation involves the stroking or rubbing of a woman vulva, especially her clitoris, with an index or middle fingers, or both. Felching is a sexual practice involving the act of orally sucking semen out of the vagina or anus of one partner. 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 in the study pool had tried coprophilia, showing no statistically significant difference between heterosexuals and homosexuals. A scene where many women have sex with one man is referred to as a reverse gang-bang. Such works have also often been subject to censorship and other legal restraints to publication, display or possession. HIV is among the infections that require such direct contact and is therefore very unlikely to be transmitted via mammary intercourse. At the end of the evening the female partners would randomly select keys from the bowl and leave with that key owner. 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 gay sex video common name for the act. His most famous model was Bettie Page, who became the first celebrity of bondage film and photography. Following the introduction of the Motion Picture Association of America film rating system, independent animation producers attempted to establish an alternative hentai sex to mainstream animation. Crush pornography features objects being crushed by an actress or actor, who generally plays momsex an overtly dominant role. They signal the presence of estrogen and the presence of sufficient fat stores for pregnancy and lactation. Internationally, hentai is a catch-all term to describe a genre of anime and manga pornography.