Jadzia Dax and Worf at a traditional Klingon wedding.
Klingon mating rituals are a series of courting traditions held by the Klingons. They tend to be somewhat violent, and involve the male reading love poetry while ducking the furniture thrown by the female. (TNG: "The Dauphin")
The mother of the father of the groom must approve of the prospective bride before a wedding can take place. (DS9: "You Are Cordially Invited")
It's not uncommon to break multiple bones during a Klingon make-out session. Also, Klingons do not like non-Klingons mating with members of their houses. (DS9: "Looking for par'Mach in All the Wrong Places")
Klingon mating rituals include combative foreplay (TNG: "Hide and Q", VOY: "Blood Fever")
In earlier evolutionary stages, Klingons had ablative armor, were extremely territorial, and spit venom at those who wanted to harm their mates. (TNG: "Genesis")