Solo pornography features performers masturbating. One-sided male nudity can also arise when a male disrobes as part of a male striptease. With second wave feminism and growth of scholarship in women history and sexuality in the 20th century, the definition of lesbian broadened, sparking a debate about sexual desire as the major component to define what a lesbian is. Sometimes, asymmetric and often intentionally uncomfortable positions are employed to heighten the psychological impact of the bondage. Felching involves drinking recently ejaculated semen from the vagina or anus. Sloppy seconds is a slang phrase for when a man has sexual intercourse with another person who already has received another man penis in the relevant orifice and is therefore wet or sloppy. Teacher and Student or Boss and Secretary pornography involves sexualized situations which take nude milfs place between an authority figure, such as a teacher or boss, and an underling, such as a student or secretary, often fake. Technically this is a form of exhibitionism rather than group sex per se. Foot videos porno gay 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 public is illegal in most countries. Individuals who can change between top/dominant and bottom/submissive roles—whether from relationship to relationship or within a given relationship—are known as switches, though the term switch in this context is occasionally seen as derogatory hentai porn and is rejected by many who might simplistically fit the definition. It has been described as professionally made porn which seeks to emulate the style of amateur pornography. Bukkake videos are a relatively prevalent niche in contemporary pornographic films. It can also be heightened by the person saying that they have to urinate. Group sex can occur between people of all sexual orientations and genders. 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.