The term bondage describes the practice of Physical restraining. Sadomasochism is practiced in isolation relatively rarely, though some masochists report biting, pinching, or even stun-gunning themselves as a prelude to, or as part of, masturbation. 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. There has been an increase in discussion and portrayal of masturbation in art, popular music, television, films, and literature. Sigmund Freud gay boy porn considered foot binding as a form of fetishism. Solo performances in gay pornography have been described in 1985 as either or both active and/or passive , whereas female solo performances are said to be exclusively passive . Solo pornography recognized with AVN Awards include hentai sex the All Alone series and All Natural: Glamour Solos. Older names for a pornographic film include stag film, and blue movie. 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. It is typically animated pornography, as the legal age to be featured in a pornographic film in Japan is 18. Many transgender people regard the term shemale as offensive, arguing that it mocks or shows a lack of respect towards the gender identity and gender expression of transgender individuals; in this view, the term emphasizes the biological sex of a person and neglects milf fuck their gender. Double penetration of the vagina, anus and mouth, can involve: Simultaneous penetration of the anus by two penises or other objects. Examples of mentally oriented practices are education games, during which the dominant requires certain forms of behavior from the submissive. Types of anal sex can also be a part of lesbian sexual practices.