The anus has a relatively high concentration of nerve endings and can be an erogenous zone, and the receiver may receive pleasure from external anal stimulation. Celebrity sex tapes are amateur or professionally-made recordings of sex acts, as performed by a gay movies celebrity and their partner. There may be more than two participants; both group sex and gang banging can be included. The term hentai is never used in this nude milfs context in Japanese. Arousal may be triggered by seeing the body movements or facial expressions of that person. Unlike the traditional definition of the term, in fetish usage a cuckold is complicit in their partner sexual infidelity hentai movies and takes masochistic sexual pleasure in it. Sex parties may be organized to enable people to engage in casual sexual activity or for swinging couples or people interested in group sex to meet, but any gathering where sexual activity is anticipated can be called a sex party. Twink pornography features younger performers, and usually features young men under 30 who identify as gay or bisexual. Clothed female, naked male is a genre of erotica featuring one or more nude men and one or more clothed women. Omorashi: The act of holding one own urine until the need to urinate is urgent, making another hold in their urine, or watching another person with an urgent need to urinate. Bottom and submissive are widely recognized terms for those partner in the relationship or activity who are, respectively, the physically receptive or controlled participants. A common way that these are depicted in a single scene is with one woman and two men performing together. The definition clash also appears with the English definition of yuri as any lesbian relationship, as opposed to its sexually explicit definition in Japan. Mammary intercourse is said by Alex Comfort to produce mutual orgasm in women with sensitive breasts , and it was one of the nine substitute exercises for penetrative sexual activities, as detailed in the Paradis Charnels of 1903.