The arousal from being desperate comes from the sensation of having a full bladder. Foot fetish pornography features heavy emphasis on the feet of the participants, either in combination with kissing and genital sex or in the context of acts such as trampling or crush fetishism. Bondage websites and bondage imagery in mainstream pornography As of 2003, specialist bondage magazines were mostly displaced by the availability of bondage material on the World Wide Web, and the presence of bondage imagery in mainstream pornographic magazines such as Nugget and Hustler Taboo magazine. 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. Even though the performers who perform in these films typically appear on many reality websites within a short span of time, most of these websites claim that each of them is an amateur. Bisexual pornography is a genre of pornography which most typically depicts one woman and two men who all perform sex acts on each other. 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. It is used, for example, at fertility clinics big tit milf to stimulate sperm donors. It is suggested that much of the obscurity and the uncertainties about female ejaculation are related to mixing up these two phenomena. Types of anal sex can also be a part of lesbian sexual practices. Hardcore pornography is pornography that depicts penetration or extreme fetish acts, or both. Both sexes sometimes apply lubricating videos porno gay substances to intensify sensation. A survey by the New York City Department of Health and Mental Hygiene found that heterosexual lesbian hentai women are more likely to bareback when engaging in anal sex than homosexual and bisexual men. Both forms of pornography generally contains nudity. A crush fetish is a fetish in which one is sexually aroused usually when someone crushes objects, food, and sometimes small animals with their body, usually under their foot, or when crushed oneself.