Though there have been numerous gang bang pornographic gay movies films since the 1980s, they usually involved no more than half a dozen to a dozen men. In the West, masturbation in private or with a momporn partner is generally considered a normal and healthy part of sexual enjoyment. Examples of mentally oriented practices are education games, during which the dominant requires certain forms of behavior from the submissive. This genre also features male-on-male fellatio through a small hole made in a bathroom divider. Lolita pornography caters to ephebophiles. 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. The term comes from the French voyeur, one who looks. Arcane or occult pornography involves sexualized situations with an occult or magical tone or performers who costume themselves in keeping with the theme, for example, a male performer dressed as a wizard. Spanking can be administered in a number of spanking positions. Behind the Green Door was one of the first pornographic films to feature sex between a white actress with a black actor . Sub-genres can also be classified into the characteristics of the performers or the type of sexual activity on which it concentrates, and not necessarily on the market to which each sub-genre appeals. Since mammary intercourse is a non-penetrative sex act, the risk of passing a sexually transmitted infection that requires direct contact between the mucous membranes and pre-ejaculate or semen is greatly reduced. Crush pornography features objects being crushed by an actress or actor, who generally plays an overtly dominant role. In Japan, point of view pornography is referred to as hamedori . Bukkake pornography involves a performer, usually female, onto whom several men or women ejaculate, usually on the face. HIV is among the infections that require such direct contact and 3d hentai is therefore very unlikely to be transmitted via mammary intercourse.