mammary intercourse 

A sexual act performed when a man places his penis between the breasts of his partner, and using the hole between the breasts, thrusts his penis back and forth until climax and ejaculation. The resulting semen that often lands on the chest, neck and chin of the female is often referred to as a pearl necklace. Also known as titfucking.

Mammary intercourse can be combined with fellatio to perform a titfuck blowjob.

mammary intercourse by AJAW February 18, 2005