When a girl has anal sex with her boyfriend so that he will propose to her.
Some women will withhold anal sex in their relationship with their boyfriend, but tell them she will do it if they get married. These women are diamond backing when they have anal sex with their boyfriends.
by someone you know well February 20, 2011
the intentional practice of unmarried heterosexual women to engage in anal intercourse prior to marriage, and then refuse afterward once that diamond ring is hers (punning on "barebacking").
Dan's really regretting this marriage: turns out his GGG fiancee turned into a diamondbacking pumpkin at the stroke of midnight after the wedding
by Ron New Mexico October 15, 2010