Koon-ut-kal-if-fee

The Koon-ut-kal-if-fee is a mating ritual conducted by the Vulcan people and has been part of their culture since before the time of Surak.(TOS novel: Vulcan's Soul).

The ritual means "marriage or challenge" and is essentially a part of the marriage ceremony. Kal-if-fee is a fight of passion in which Vulcans fight over another's mate. These fights can be deadly as they can lead to the death of one of the parties and outsiders are not permitted to interfere during the ritual. These fights tend to occur when two Vulcan's desire the same mate during the Pon farr or when the female mate rejects the male's proposal that was made during childhood by the parents. As part of the ritual, the female can choose a defender to fight for her which can include either herself, another male or even an alien. (TOS episode: Amok Time, VOY episode: Blood Fever)