Solo pornography recognized with AVN Awards include the All Alone series and All Natural: Glamour Solos. Some anthropologists and sociobiologists believe that breast fetishism derives from the breasts similarity to buttocks, but instead provide sexual attraction from the front of the body. The Silent Duck, also called Duck-Billing, is the technique often used in which the person engaging in hand insertion shapes the hand to resemble a duck beak. A bisexual threesome may involve a man having sex with a man and a woman, the woman having sex with a man and a woman, or all three having sex with each other. The loose and direct camera work often includes tight shots of the genitalia, unlike some traditional porn. Clothed male, naked female is one-sided female nudity in which one or more females are nude while one or gay cock more men are clothed. A sex party is a gathering at which sexual activity takes place. Since mammary intercourse is a non-penetrative sex act, the risk of passing a sexually transmitted infection that requires direct contact between the mucous membranes and pre-ejaculate or semen is greatly reduced. Reality and voyeur pornography, animated videos, and legally prohibited acts also influence the classification of pornography. 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 hentai porn statistically milf xxx significant difference between heterosexuals and homosexuals. It contains graphic sexual activity and visible penetration. Rainbow parties were covered on The Oprah Winfrey Show in 2003, and became the subject of a juvenile novel called Rainbow Party. Some people get sexual pleasure by inserting objects, such as urethral sounds, into the urethra , a practice known as urethral play or sounding. It is also known colloquially as gushing or squirting, although these are considered to be different phenomena in some research publications.