A somewhat controversial ejaculation control technique is to put pressure on the perineum, about halfway between the scrotum and the anus, just before ejaculating. Sadomasochism does not imply enjoyment through causing or receiving naked milf pain in other situations . Transsexual porn star Wendy Williams has stated that transsexual porn is classified as Straight Specialty. 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. But starting with The World Biggest Gangbang , starring Annabel Chong, the pornographic industry began producing a series of films ostensibly setting gangbang hentai porn records for videos porno gay most consecutive sex acts by one person in a short period. The term soft crush refers to the more common fetish surrounding videos involving inanimate objects or small invertebrates being crushed, while the term hard crush refers to such videos involving larger animals with vertabrae, and arguably more pain-susceptible animals . Entacle erotica describes a type of pornography most commonly found in Japan which integrates traditional pornography with elements of bestiality and a fantasy, horror, or science-fiction theme. Going back at least as far as the Christy twins in the 1970s, depictions of incest and particularly incest between twins has been a feature of gay pornography. Group sex can occur between people of all sexual orientations and genders. The buttocks in human females thus contain more adipose tissue than in males, especially after puberty. Unlike erotic films, pornographic films contain explicit sexuality and do not claim any artistic merit. A celebrity may allow such a recording to surface willingly, as part of a publicity stunt. The related term twinkle-toes, which implies that a man is effeminate, tends to be used in a derogatory manner. Originating in Japan in the 1980s, the genre subsequently spread to North America and Europe, and crossed over into gay pornography.