The initialism BDSM includes psychological and physiological facets: Bondage & Discipline momsex Dominance & Submission Sadism & Masochism Types of Play This model for differentiating among these three aspects of BDSM is increasingly used in literature today. 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. Typically features adult, masculine men with varying degrees of muscle, body fat, and body hair, akin to beefcakes, or bears. A scene where many women have sex with one man is referred to as a reverse gang-bang. Common phrases used to refer to these individuals are chicks with dicks or the derogatory term shemale, although these are generally considered pejorative among transwomen. Coprophilia , also called scatophilia or scat , is the paraphilia involving sexual arousal and pleasure from feces. Mammary intercourse is known as titty-fucking, titfuck, or a titjob in the United States, as well as tit wank or French fuck in the United Kingdom - the latter term dating back to the 1930s; while a more jocular equivalent is a trip down mammary lane. Such grounds and even the definition anime hentai of pornography have differed in various historical, cultural, and national contexts. It has since become popular enough with couples to be discussed during an episode of Sex and the City. The resulting consent and understanding is occasionally summarized in a written contract, which is an agreement of what can and cannot take place. Works in this genre may explore philosophical, political or gay cock social issues. In humans, females generally have more round and voluptuous buttocks, caused by estrogen that encourages the body to store fat in the buttocks, hips, and thighs. It is geared towards heterosexual men, who most typically define a threesome as such. Standing up, a chair, the corner of an item of furniture, or even a washing machine can be used to stimulate the clitoris through the labia and clothing.