Both sexes sometimes apply lubricating substances to intensify sensation. Examples of mentally oriented practices are education games, during which the dominant requires certain forms of behavior from the submissive. Real school shots or videos which are sexualized may violate privacy laws in some countries. 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. Spanking can be administered in a number of spanking positions. Perhaps following the example set by gay pornography, they have become a popular subgenre within heterosexual pornography since the turn of the century, featuring both vaginal and anal ejaculations. As a form of non-penetrative sex, it can be done for its own enjoyment or as foreplay. They may be noted for using risqué themes, graphic violence, sexuality or black comedy in a manner that is unsuitable for younger audiences. A scene where many women have sex with one man is referred mature milfs to as a reverse gang-bang. Masturbation is the self-sexual stimulation of the genitals for sexual arousal or other sexual pleasure, usually to the point of orgasm. Additionally, the buttocks give an indication of the shape and size of the pelvis, which impacts reproductive capability. The introduction of the home video and Internet saw a boom in the worldwide gay movies porn industry that generates billions of dollars annually. 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 hentai sex his or her mouth and then passes it to the mouth of the other, usually through kissing. Patricia Hill Collins, an African-American writer, theorizes that this is derived from a stereotype that those of black descent are promiscuous, and their buttocks are objectified by porn as a result.
