Lesbian pornography made for women is usually made by women, and usually features women who identify as lesbian or bisexual. Such films continued to be produced but could only be distributed by underground channels. As in B/D, the declaration of the Top/Bottom may be required, though sadomasochists may also play without any Power Exchange at all, with both partners equally in control of the play. It is commonly depicted in pornography, but very rarely in mainstream momporn cinema. The term lesbian is also used with regard to sexual identity or sexual behavior, regardless of sexual orientation, or as an adjective to characterize or associate nouns with female homosexuality or same-sex attraction. Sometimes special furniture is used, such as a queening stool or smotherbox. The padding may also muffle noises from the outside, causing a relaxation effect and heightening their other senses. Matsuo used amateur actresses in his videos, and he usually traveled to their hometowns for the filming. Ethnic pornography is a genre of pornography that features performers anime hentai of specific ethnic groups, or depictions of interracial sexual activity. While bondage is a very popular variation within gay cock the larger field of BDSM, it is nevertheless sometimes differentiated from the rest of this field. A somewhat controversial ejaculation control technique is to put pressure on the perineum, about halfway between the scrotum and the anus, just before ejaculating. People may engage in anilingus for its own sake, before anal fingering or penetration, or as part of foreplay. Group sex is sexual behavior involving more than two participants. Twink pornography features younger performers, and usually features young men under 30 who identify as gay or bisexual. Masturbation has been depicted in art since prehistoric times and is mentioned and discussed in very early writings. Emetophilia pornography involving vomiting and gagging. In the context of consensual erotic activities, sadism and masochism are not strictly accurate terms; there is a significant difference from the medical or psychological usage of both terms.