In modern BDSM vernacular, the queening stool allows open access to the crotch while seated. Interracial pornographic films have experienced an explosion in popularity, becoming one of the fastest-growing gay boy porn and biggest-selling genres. Tentacle rape or shokushu goukan is found in some horror or hentai titles, with tentacled creatures having sexual intercourse with female characters. Many men who like trans partners of any variety, known as tranny chasers, do not necessarily identify as gay themselves. The Silent Duck, also called Duck-Billing, is the technique often used in which the person engaging in hand insertion shapes the hand to resemble a duck beak. The concept of lesbian, to differentiate women with a shared sexual orientation, is a 20th-century construct. A female dominant in a master/slave relationship is often termed a Mistress, not to be confused with the colloquial usage of mistress as a kept sexual partner without a similarly formalized power relationship. Greater economic and social freedom allowed them gradually to be able to determine how they could form relationships and families. Transsexual pornography is a genre of pornography. The term applies to the depiction of the act rather than the act itself, and so does not include live exhibitions like sex shows and striptease. The buttocks in human females thus contain more adipose tissue than in males, especially after puberty. Films with risqué content commenced to be produced soon after the invention of the motion picture in the 1880s. A pearl necklace is a slang term referring to a sexual act in which a man ejaculates semen on or near the neck, chest, or breast of another person. This fetish sometimes originates from childhood memories of needing, or of seeing another needing, to urinate. When he is in position the cover is closed. Both forms of pornography generally contains nudity. Female dominance refers to BDSM relationships and BDSM scenes in which the dominant partner is female. Entacle erotica describes a type of pornography most commonly found in Japan which integrates traditional momporn pornography with elements of bestiality and a fantasy, horror, or science-fiction theme.