Mammary intercourse describes a sex act, performed as foreplay or as non-penetrative sex, that involves the stimulation of the male penis by the female breasts. Commonly, this sex act involves the man placing his penis in the woman's cleavage and thrusting between her breasts, while the breasts are squeezed around the penis for additional stimulation. Mammary intercourse is sometimes combined with fellatio.
When mammary intercourse continues to the point of ejaculation, the semen can land on the breasts, face, or in the mouth of the woman. A slang term for the appearance of semen landing on the woman's upper chest, neck, or shoulders is "pearl necklace".
Several slang terms refer to mammary intercourse, such as titfuck or titty fuck in the United States, tit wank or French fuck in the United Kingdom.