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. Multiple men and women Bisexual pornography features porn milf one woman and two men who all perform sex acts on each other. However, bisexual pornography is often placed near the gay section in adult video stores, since many consumers are gay men. Transsexual pornography is a genre of pornography. The inside of a smotherbox is often padded to provide support for their neck and prevent their head from moving. The name gay twink porn is a reference to gonzo journalism, in which the reporter is part of the event taking place. Mammary intercourse is a sex act, performed as foreplay or as non-penetrative sex, that involves the stimulation of the male penis by the female breasts and vice versa. A sex party is a gathering at which sexual activity takes place. Related genres include: Amateur pornography originally referred only to hentai movies pornography produced by amateurs but now also includes professionally made pornography designed to appear as if it were amateur. In the fetish cuckolding subculture, it is most common for the female to take on the sexually dominant role and the male the submissive role, however, female subs, sometimes referred to as cuckqueans, also exist. This can, however, redirect semen into the bladder . Shibari is a Japanese word that literally means to tie or to bind. Jerk off instruction features a performer encouraging or instructing the viewer to masturbate, often culminating in a countdown at the end of which the viewer is invited to induce orgasm. Depictions of male and female masturbation are common in pornography, including gay pornography. Sexologist Alfred Kind suggested that the buttocks is the primary sexual presentation site in primates. It is also known colloquially as gushing or squirting, although these are considered to be different phenomena in some research publications.