The first explicit pegging scene is believed to have been in the 1975 pornographic film The Opening of Misty gay sex video Beethoven. Contrary to the other two types, B/D does not define the Tops and Bottoms itself, and is used to describe the general activities with either partner being the receiver and the giver. Concerted deployed sexual rejection exercised on the partner can be an aspect of Dominance and Submission as well. When used as an alternative to penile-vaginal penetration, the goal may be to preserve virginity or to prevent pregnancy. In general, BDSM play is usually structured such that it is possible for the consenting partner to withdraw his or her consent during a scene; for example, by using a safeword that was agreed on in advance. Many fantasies include the macrophile shrinking before a normal sized woman or keeping his or her normal height while the partner grows in size. Commenting on why there are not as many female macrophiles, psychologist Helen Friedman theorized that because women in most societies already view men as dominant and powerful, there no need for them to fantasize about it. Preggo pornography features pregnant performers and may include erotic lactation as a fetish. Bondage websites and bondage imagery in mainstream pornography As of 2003, specialist bondage magazines were mostly displaced by the availability of bondage material on the World Wide Web, and the presence of bondage imagery in mainstream pornographic magazines such as Nugget and Hustler Taboo magazine. Lying face down on a comfortable surface such as a mattress or pillow, the penis can be rubbed against it. 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 lesbian milfs in the study pool had tried coprophilia, showing no statistically significant difference between heterosexuals and homosexuals. The term anime hentai bondage describes the practice of Physical restraining.