BDSM communities generally welcome anyone with a non-normative streak who identifies with the community; this may include cross-dressers, extreme body mod enthusiasts, animal players, latex or rubber aficionados, and others. The concept of lesbian, to differentiate women with a shared sexual orientation, is a 20th-century construct. The prostate gland is one of the organs that contributes fluid to semen. Tentacle erotica can be consensual, but frequently contains elements of non-consensual sex. The definition clash also appears with the English definition of yuri as any lesbian relationship, as opposed to its sexually explicit definition in Japan. It is sometimes combined with BDSM features. There has been an increase in discussion and portrayal of masturbation in art, popular music, television, films, and literature. Shibari is a Japanese word that literally means to tie or to bind. Some women who engage in same-sex sexual activity may reject not only identifying as lesbians but as bisexual as well, while other women self-identification as lesbian may not align with their sexual orientation or sexual behavior; sexual identity is not necessarily the same as one sexual orientation or sexual behavior, due to various reasons, such as the fear of identifying their sexual orientation in a homophobic setting. In some scenes or relationships it may be impossible for consent to be withdrawn in the middle of a scene, or the bottom may have the ability to revoke consent for a relationship as a whole, but not for a particular scene. Advocates of RACK argue hentai videos that SSC can hamper discussion of risk because no activity is truly safe, and that discussion of even low-risk possibilities is necessary for truly informed consent. Femdom features BDSM scenes in which the dominant porn milf partner is female. This fetish sometimes originates from childhood memories gay twinks of needing, or of seeing another needing, to urinate. BDSM actions can often take place during a specific period of time agreed to by both parties, referred to as play, a scene or a session.