With second wave feminism and growth of scholarship in women history and sexuality in the 20th century, the definition of lesbian broadened, sparking a debate about sexual desire as the major component to define what a lesbian is. Also see POV. The name of the practice, when it is done in a repeated in-and-out motion, is derived from its passing resemblance to the dipping of a tea bag into a cup of hot water as a method of brewing tea. Technically this is a form of exhibitionism rather than group sex per se. 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. Transsexual people Transman pornography features performers who were born female and who medically transitioned to male. Often a dominant woman, she may be called a Dom, Domme /ˈdɒm/, Femdomme, momsex Domina, or Dominatrix, depending on context or personal preference. Rough sex pornography is similar to pornography featuring sadomasochism, and typically features a Top who humiliates and/or degrades a Bottom while being physically violent towards them. Initially, few animation studios in the United States attempted to produce animation for adult audiences, but later examples of animation produced for adults would gain mainstream attention and success. Fisting pornography features the insertion of an entire hand into a performer vagina or anus. The principal characteristic of voyeurism is that the voyeur does not normally interact directly with the subject of his/her interest, who is often unaware of being observed. Sadomasochism does not imply enjoyment through causing or receiving pain in other situations . Transsexual porn star Wendy Williams has stated that transsexual porn is classified as Straight Specialty. The buttocks videos gays in human females thus contain more adipose tissue than in males, especially after puberty. A variant of this is known hentai porn as ATOM or ATOGM where the insertive partner removes his penis from one recipient anus and inserts it into a second recipient mouth.