The koon-ut-kal-if-fee is a Vulcan mating ritual which literally means "marriage or challenge" and is fundamentally a wedding ceremony. Kal-if-fee is a "passion fight" in which a Vulcan challenges another over a mate. During the 23rd century, the fights were over when one was killed. The conflict is generally initiated when either two adult males wish to mate with one female during the pon farr, or when the female does not want the male that was arranged for her at childhood. The female can choose any defender she wants, including herself or an alien. (TOS: "Amok Time"; VOY: "Blood Fever")

It is suspected that both challengers break their blood fever, assuming one of them is not killed first. (VOY: "Blood Fever")