Female masturbation involves the stroking or rubbing of a woman vulva, especially her clitoris, with an index or middle fingers, or both. The current public acceptance of celebrities with sex tapes is speculated by Joe Levy, executive editor of Rolling Stone, to be due to the easy availability of pornography, as well as couples more commonly making their own tapes due to the prevalence of video cameras. Bra pornography involves women or men dressed in bras. Felching is a sexual practice involving the act of orally sucking semen out of the vagina or anus of one partner. The purpose of this kind of agreement is primarily to encourage discussion and negotiation in advance, and then to document that understanding for the benefit of all parties. In these research publications, it is suggested that real female ejaculation is the release of a very scanty, thick, and whitish fluid from the female prostate, while the squirting or gushing shown frequently in pornography is a different phenomenon, the expulsion of clear and abundant fluid, which has been shown to be a diluted fluid from the urinary bladder. Others consider the position to involve the man squatting over his reclined partner while the testicles are repeatedly raised and lowered into the mouth. Medical pornography involves sexualized medical, often fake, including gynecological pelvic examinations, rectal examinations, and pelvic or gynecological ultrasounds. Testosterone discourages lesbian hentai fat storage in these areas. Gonzo pornography is a style of pornographic film that attempts to place the viewer directly into the scene. A bisexual threesome may involve a man having sex with a man and a woman, the woman having sex with a man and a woman, or all three having sex with each other. Unlike smothering, in facesitting the bottom partner is not deprived of air. It therefore has the connotation of being wild, dangerous, porn milf and fun. Rimjob pornography videos gays centers around anilingus. Works in this genre may explore philosophical, political or social issues.