Some aspects of the research community distinguish between female ejaculation and what is colloquially known as squirting or gushing. Sub-genres can also be classified into the characteristics of the performers or the type of sexual activity on which it concentrates, and not necessarily on the market to which each sub-genre appeals. In the gay pornography industry, which uses amateurs as well as professional actors, the term gay-for-pay refers to actors labeled or believed to be straight but who engage in same-sex sexual activities for money. Oral sex pornography frequently features a person performing fellatio, and less frequently cunnilingus. Point of view pornography is adult entertainment filmed to look as if the watcher were experiencing the sex act themselves. In Japanese, this natural-fibre rope is known as asanawa; the Japanese vocabulary does not make a distinction between hemp and jute. Particular areas and processes of the body that change during pregnancy may also become the focus of psychological investment, but nudity gay boy porn or sexual activity is not always essential, and in some cases actual pregnancy is not necessary to invoke arousal. Clothed female, naked male pornography features naked men and clothed women; typically, the women humiliate and abuse the men or perform fellatio and/or handjobs on the men. If one person is penetrated by two objects, it is generically called lesbian milfs double penetration . Cum shots typically do not appear in girl-girl scenes and orgasm is normally implied by utterances, cinematic conventions, or body movement. Voyeur pornography may also include shots of topless women on topless beaches who are unaware of the cameras but may legally be photographed due to the public setting. These styles are much closer to the style of bondage scenes in mainstream television. Pornography may fall into more than one genre. Studies have found that masturbation is frequent in humans of both sexes and all ages, although there is variation. Among swinging hentai videos couples, one of the two partners is often the driving force and the other is more passive-supportive of the addition of additional sex parties.