See also Gay-for-pay. Rubber pornography involves hentai movies rubber, latex, and similar materials. Crush pornography features objects being crushed by an actress or actor, who generally plays an overtly dominant role. Smotherboxes are usually custom made pieces of furniture that may have a special significance for their users. Some are aroused from wetting their diapers, others like messing their diapers. 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. The activity is done by itself or as a part of or prelude to other activities which many times involve sex. During anal sex, male pleasure can be particularly derived from the prostate, which can lead to an orgasm and ejaculation. A celebrity sex tape is typically an amateur pornographic video recording involving one or more celebrity famous person which has, intentionally or unintentionally, been made available publicly. Shotacon : Similar to Lolicon, this genre involves prepubescent or under-aged boys between the ages 6–12. A threesome is videos porno gay also depicted with one woman and two men who all perform sex acts on each other . It is typically animated pornography, as the legal age to be featured in a pornographic film in Japan is 18. Medical pornography involves sexualized medical, often fake, including gynecological milf fuck pelvic examinations, rectal examinations, and pelvic or gynecological ultrasounds. No causal relationship is known between masturbation and any form of mental or physical disorder. Cartoon pornography is the portrayal of illustrated or animated fictional characters in erotic or sexual situations. In contrast, a celebrity may take the route of openly releasing the tape and benefit directly from royalties as well as indirectly from the publicity. Others consider the position to involve the man squatting over his reclined partner while the testicles are repeatedly raised and lowered into the mouth.