It is used, for example, at fertility clinics to stimulate sperm donors. 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. Sadomasochism is practiced in isolation relatively rarely, though some masochists report biting, pinching, or even stun-gunning themselves as a prelude to, or as part of, momporn masturbation. The concept of lesbian, to differentiate women with a shared sexual orientation, is a 20th-century construct. In Japanese, this natural-fibre rope is known as asanawa; the Japanese vocabulary does not make a distinction between hemp and jute. Double penetration of the vagina, anus and mouth, can involve: Simultaneous penetration of the anus by two penises or other objects. Some men also enjoy anal stimulation, hentai sex with fingers or otherwise, without any prostate stimulation. The full-weight body-pressure, moisture, sex odors and darkness can be perceived as powerful sexual attractions or compulsions. The genres of pornography are based on the type of activity featured and the category of participants, for example mateur pornography is a category of pornography that features models, actors or non-professionals performing without pay, or actors for whom this material is their only paid modeling work. Solo pornography recognized with AVN Awards include the All Alone series and All Natural: Glamour Solos. Female ejaculation is the expulsion of fluid by the paraurethral ducts through and around the human female urethra during or before an orgasm. Threesome can also refer to a love triangle, a three-way romantic relationship. On May 27, 2010 the television program The Doctors discussed the topic with dozens of teens, parents, and professionals. The term Asiaphile is sometimes used gay fuck to describe the same phenomenon as is yellow fever . 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.