Although pornography has usually focused on heterosexuality, due to the prevalence of the heterosexual orientation, explicit gay material has a long history as well, which reaches back to Greek antiquity, if not to prehistory. Incest itself is largely taboo, and is a crime in many countries. It has also been recommended as a form of foreplay or safer sex. Depictions of male and female masturbation are common in pornography, including gay pornography. These scenes may either have the cameraman directly engaging in sex or merely filming others having sex. This technique may include the use of a simulacrum, or artificial vagina. Shemale is a term primarily used in sex work to describe a trans woman with male genitalia combined with female secondary sex characteristics, usually including augmented female breasts, from breast augmentation and/or use of hormones. It is commonly gaysex depicted in pornography, but very rarely in mainstream cinema. In human sexuality, a threesome is sexual activity that involves three people at the same time. Simultaneous penetration of the mouth and either the vagina or anus. Voyeurism: Seeing another urinate without the person knowledge either through video taping by a hidden camera, or by lurking naked milf in locations where people are urinating or are likely to have an urge to urinate. Softcore gay pornography also exists; it at one time constituted the genre, and may be produced as beefcake pornography for heterosexual female and homosexual male consumption. Mutual masturbation can be practiced by males or females in pairs or groups with or without actually touching another person as indicated by the following examples of contact versus non-contact scenarios: Non-contact mutual masturbation Two people masturbating in the presence of each other but not touching. Hugo Ohira, hentai sex director of marketing for Silvercash, rhetorically asks Who does not like spewing their load on a pretty young face? Double Stuffed , Double Vaginal , or Double Anal pornography involves the penetration of one orifice by two penises or other objects.