Detective magazines, comic books and early fetish magazines In the early 20th century, Detective magazines covertly provided a way of publishing bondage imagery. The term comes from the French voyeur, one who looks. The most common male masturbation technique is simply to hold the penis with a loose fist and then to move the hand up and down the shaft. The term is typically used by the cinematographer within the narrative framework of a pornographic film, and since the 1970s has become a leitmotif of the hardcore genre. Behind the Green Door was one of the first pornographic films to feature sex between a white actress with a black actor . Works in this genre may explore philosophical, political or social issues. Types of anal sex can also be a part of lesbian sexual practices. There are number of types of sex parties: Swinger party/gathering A swinger party or partner-swapping party is a gathering at which individuals gay videos or couples in a committed relationship can engage in sexual activities with others as a recreational or social activity. The term has origins in the Greek language . Reality and voyeur pornography, animated videos, and legally prohibited acts also influence the classification of pornography. They may regard it as an enhancing element of their sex lives or as their primary form of sexual activity. A 2009 study found that heterosexual male fat admirers preferred females that were clinically overweight and rated both overweight and obese women more positively than slighter individuals. Following World War II, during a period of social repression when governments actively persecuted homosexuals, women developed networks to socialize with and educate each other. On the other hand, the masochist enjoys being hurt, humiliated, or suffering within the consensual scenario. 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.