Pornography may fall into more than one genre. The niche popularity grew significantly in momporn the latter half of the first decade of the 2000s. A study of the condom usage habits of New Zealand sex workers said that they offered various safe sex alternatives to vaginal sex to clients who refused to wear a condom. Sadism describes sexual pleasure derived by inflicting pain, degradation, humiliation on another person or causing another person to suffer. Studies have found that masturbation is frequent in humans of both sexes and all ages, although there is variation. 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. The queening stool is also related to a smotherbox, which also allows the person under the seat to be locked in place, restrained by the neck as in a set of stocks. Masturbation is the self-sexual stimulation of the genitals for sexual arousal or other sexual pleasure, usually to the point of orgasm. When used as an alternative to penile-vaginal penetration, the goal may be to preserve virginity or to prevent pregnancy. 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. Irrespective of the legal or social view of pornography, it has been used in a number of contexts. Lesbian hot gay sex 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 gay hentai 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 . Internationally, hentai is a catch-all term to describe a genre of anime and manga pornography.