One-sided male nudity can also arise when a male disrobes as part of a male striptease. Foot fetishism, foot partialism, foot worship, or podophilia is a pronounced sexual interest in feet. The Japanese sex industry uses the term Paizuri . See Gay-for-pay. Anal sex or anal intercourse is generally the insertion and thrusting of the erect penis into a person anus, or anus and rectum, for sexual pleasure. It is also often mixed with other fetishes in practice, such as voyeurism, denial, etc. Partners can engage in penetrative sex, known as full swap, or choose to soft swap in which they engage only in non-penetrative sex. Though the term anal sex most commonly means penile-anal penetration, sources sometimes use the term anal intercourse to refer exclusively to penile-anal penetration, and anal sex to refer to any form of anal sexual activity, especially between pairings as opposed to anal masturbation. Pornography is generally classified as either softcore or hardcore pornography. Pornography can be classified according to the physical characteristics of the participants, fetish, sexual orientation, etc., as well as the types of sexual activity featured. Pornographic films present sexual fantasies and usually gay fuck include erotically stimulating material hentai porn such as nudity. Another variant of reality pornography consists of normal couples that are filmed by professionals, in which case the only obvious distinction from amateur pornography is the higher quality of production, filming and editing. Mutual masturbation is a sexual act where two or more people stimulate themselves or one another sexually, usually with the hands. A large part of the popularity momsex of these videos is seeing how regular and normal the girls are in real-life. Group sex can occur between people of all sexual orientations and genders. Actors are mostly amateur; any well-known actors in bisexual porn tend to be from the gay pornography industry. The padding may also muffle noises from the outside, causing a relaxation effect and heightening their other senses.