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. Breeding is sometimes followed by felching, which involves sucking the semen from the partner anus. These styles are much closer gay movies to the style of bondage scenes in mainstream television. Some people get sexual pleasure by inserting objects, such as urethral sounds, into the urethra , a practice known as urethral play or sounding. Smotherboxes are usually custom made pieces of furniture that may have a special significance for their users. Milking pornography features lactating women being milked or milking themselves . Particularly, some pornography in this genre features butch women, who are almost never seen in mainstream pornography. Cartoon pornography includes, but is not limited big tit milf to, hentai and parody renditions of famous cartoons and comics. They may be noted for using risqué themes, graphic violence, sexuality or black comedy in a manner that is unsuitable for younger audiences. A facial is a term for the sexual activity in hentai sex which a man ejaculates semen onto the face of one or more sexual partners. Mammary intercourse has sometimes been considered a perversion. Bra pornography involves women or men dressed in bras. A threesome is also depicted with one woman and two men who all perform sex acts on each other . Instead, all five fingers are kept straight and held as close together as possible , then slowly inserted into a well lubricated vagina or rectum. Positions can also be chosen specifically for added effects such as increased humiliation, elevation and suspension. People may also find masturbating with friends helps lift the stigma they feel surrounding the act. Many times a top actor will then be sought as a bottom and the debut is often treated as a notable event or even its own release.