The niche popularity grew significantly in the latter half of the first decade of the 2000s. Reality and voyeur pornography, horny milfs animated videos, and legally prohibited acts also influence the classification of pornography. There is, however, no third party camera work involved. Biological anthropologist Helen B. Clothed male, naked female is one-sided female nudity in which one or more females are nude while one or more men are clothed. Snowballing or snowdropping is the human sexual practice in which one person takes someone else semen into his or her mouth and then passes it to the mouth of the other, usually through kissing. Bukkake pornography involves a performer, usually female, onto whom several men or women ejaculate, usually on the face. Participants who exert sexual control over their partners are known as dominants or tops while participants who take the passive, receiving, or obedient role are known as submissives or bottoms. Sexual relations between women have been illustrated as well as narrated, but much of the written material from the early modern period has been destroyed. The other person may do the same during or after. Types of anal sex can also be a part of lesbian sexual practices. In S/M, the Sadist is usually the Top and the Masochist the Bottom, but these roles are frequently more complicated hentai videos or jumbled . The act may be carried out face to face, videos porno gay or head to tail, with the woman recommended to be on top if she has smaller breasts. Group sex pornography features at least two men and two women , usually more, who all perform sex acts on each other. Hentai narrow Japanese usage and broad international usage are often incompatible. The queening stool is also related to a smotherbox, which also allows the person under the seat to be locked in place, restrained by the neck as in a set of stocks. 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.