In the 1970s, the hardcore pornography genre introduced the stereotypical cumshot scene as a central element of the hardcore film, in which the male actor ejaculates in a way ensuring maximum visibility of the act itself. Boot fetishism is a sexual fetish dedicated to boots. One-sided male nudity can also arise when a male disrobes as part of a male striptease. However, the tradition of bondage magazines continues in the form of art books of bondage photographs, published videos gays by mainstream publishers such as Taschen. Targets the male audience, but is much less popular than Yaoi. Actual upskirt or downblouse shots may violate privacy laws in some countries. Currently, animated television series aimed at adults are some of the most popular and critically acclaimed forms of entertainment. Bisexual pornography is a genre of pornography which most typically depicts one woman and two men who all perform sex acts on each other. Teacher and Student or Boss and Secretary pornography involves sexualized situations which take place between an authority figure, such as a teacher or boss, and an underling, such as a student or secretary, often fake. These scenes may either have the cameraman directly engaging in sex or merely filming others having sex. Although pornography has usually focused on heterosexuality, due to the prevalence of the heterosexual orientation, explicit gay material has a long history as well, which reaches back to Greek antiquity, if not to prehistory. For uncircumcised males, stimulation of the penis in this way comes from the pumping of the foreskin, in which the foreskin is held and slid up and down over the glans, which depending on foreskin length, is completely or partially covered and then uncovered in a rapid motion. When he is in position the cover nude milfs is closed. In September 2003 the BBC reported on the new dogging craze. Such explicit sexual interaction is seen only rarely in public play spaces, and it is sometimes specifically banned hentai porn by the rules of a party or playspace.