A woman can use a secondary vibrator, between the dildo and her genitals, to get pleasure from pegging. A study of 164 males in Finland from two SM clubs found that 18.2% had engaged in coprophilia; 3% as a sadist, 6.1% as a masochist, and 9.1% as both. 18% of heterosexuals and 17% of homosexuals in the study pool had tried coprophilia, showing no statistically significant difference between heterosexuals and homosexuals. Kurt Wild, who appeared as a bottom in Lucas Entertainment Gigolos, is married to a woman and has three children. The cover can have hinges or be a separate part. Group sex most commonly takes place in a private sex party or semi-public swinger gathering, but may also take place at massage parlors or brothels or, in some jurisdictions, at purpose-built locations such as sex clubs. Pornographic films are typically categorized as either softcore or hardcore pornography. New York photographer Irving Klaw also published illustrated adventure/bondage serials by fetish artists Eric Stanton, Gene Bilbrew, Adolfo Ruiz and others. In POV porn, the shooting style is generally similar to gonzo pornography, with the person receiving sexual gratification holding the camera him or herself—aiming it down at the actress or actor who is performing the sex act. Particular areas gay sex videos and processes of the body that change during pregnancy may also become the focus of psychological investment, but nudity or sexual activity is not always essential, and in some cases actual pregnancy is not necessary to invoke arousal. Mutual masturbation, mutual manual stimulation of the genitals between partners, can be a substitute for sexual penetration. Exhibitionism: Becoming noticeably desperate or wetting oneself with the express purpose of being seen by strangers. Gay pornography is the representation of sexual activity between males. Works in this genre may explore philosophical, political or social issues. A related term used in the genre is the term cougar, which implies an older woman as predator.