Buttocks are sometimes emphasized in pornography, where they are often referred to as booty. Lesbian pornography typically features a wider range of appearances and body types than is typical of mainstream pornography. People may experience pleasure from anal sex by stimulation of the anal nerve endings, and orgasm may be achieved through anal penetration – by indirect stimulation of the prostate in men, indirect clitoral/G-spot stimulation in women, and associated sensory nerves . In the 18th and 19th centuries, some European theologians and physicians described it as heinous, deplorable, and hideous, but during the 20th century, these taboos generally declined. Most bisexual porn is made by small production companies rather than the major studios. Typically features adult, masculine men with varying degrees of muscle, body fat, and body hair, akin to beefcakes, or bears. Works in this genre may explore philosophical, political or social issues. A study of the condom usage habits of New Zealand sex hentai porn workers said that they offered various safe sex alternatives to vaginal sex to clients who refused milf fuck to wear a condom. Lolita pornography that features actual teenage girls under the age of 18 is illegal in most countries and treated as child or youth pornography. The resulting consent and understanding is occasionally summarized in a written contract, which is an agreement of what can and cannot take place. 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. Pegging films include Strap It On , Babes Balling Boys , Strap Attack, Strap-on Sirenz, Strap-on Chicks, Boss Bitches , various movies produced by LEDA Studios, and San Francisco-based Men In Pain. The term has also gay bear porn applied to other professions and even companies trying to appeal to a gay demographic. Internationally, hentai is a catch-all term to describe a genre of anime and manga pornography.