The resulting consent and understanding is occasionally summarized in a written contract, which is an agreement of what can and cannot take place. 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. Medical pornography involves sexualized medical, often fake, including gynecological pelvic examinations, rectal examinations, and pelvic or gynecological ultrasounds. Some are aroused from wetting their diapers, others like anime hentai messing their diapers. The glans itself may widen and lengthen as the stimulation continues, becoming slightly darker in colour, while the gliding action of the foreskin reduces friction. Patricia Hill Collins, an African-American writer, theorizes that this is derived from a stereotype that those of black descent are promiscuous, and their buttocks are objectified by porn as a result. Coprophilia , also called scatophilia or scat , is the paraphilia involving sexual arousal and pleasure from feces. Such documents have not been recognized as being legally binding, nor are they intended to be. It is the most common form of sexual fetishism videos porno gay for otherwise porn milf non-sexual objects or body parts. Reading or viewing pornography, sexual fantasy or other erotic stimuli may lead to a desire for sexual release such as by masturbation. In recent years, however, many celebrities have benefited from the publicity resulting from the release of a sex tape. Studies among BDSM practitioners in the US have shown that about half of all men find the idea of bondage to be erotic; many women do as well. While some fantasize about a giantess who is slightly taller than himself, others are interested in giantesses that are hundreds or even thousands of feet tall. The initialism BDSM includes psychological and physiological facets: Bondage & Discipline Dominance & Submission Sadism & Masochism Types of Play This model for differentiating among these three aspects of BDSM is increasingly used in literature today.