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. 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. Am Abend , one of the earliest pornographic films that have been collected at the Kinsey Institute for Research in Sex, Gender, and Reproduction, starts mature milfs with a female masturbation scene. The Japanese sex industry uses the term Paizuri . Foot fetishism, foot partialism, foot worship, or podophilia is a pronounced sexual interest in feet. The legal status of masturbation has also varied through history and masturbation in celebrity sex videos public is illegal in most countries. The first pegging scene appears to have been in the non-pornographic 1970 film Myra Breckinridge, based on the novel of the same name by Gore Vidal, although it was not explicit. Enema pornography involves adults given enemas to others, often fake. Unlike erotic films, pornographic films contain explicit sexuality and do not claim any artistic merit. It is also often mixed with other fetishes in practice, such as voyeurism, denial, etc. In the context of consensual erotic activities, sadism and masochism are not strictly accurate terms; there is a significant difference from the medical or psychological usage of both terms. Others involve partners who naturally have a significant difference in size. Fisting pornography features the insertion of an entire hand into a performer vagina or anus. Clothed female, naked male is a genre of erotica featuring one or more nude men hentai videos and one or more clothed women. Sloppy seconds is a slang phrase for videos gays when a celeb gossip man has sexual intercourse with another person who already has received another man penis in the relevant orifice and is therefore wet or sloppy.