Worf and K'Ehleyr involved in the Klingon mating ritual.
Klingon mating rituals are a series of courting traditions held by the Klingons. Klingon mating rituals include combative foreplay (TNG: "The Emissary", TNG: "Hide and Q", VOY: "Blood Fever"). The ritual begins with each participant sniffing the other's right arm/hand. Then each grips the other's right hand as to cause bleeding. Klingon's traditionally mate for life, and take commitment oaths after the first encounter. (TNG: "The Emissary") This ritual is not always carried out when mating occures between a Klingon and a member of another race. (DS9: "Penumbra"). It can only assumed that the actual act of Klingon sexual congress is similar the the human act.
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. Jadzia Dax describes the Klingon mating ritual as the participants "jumping on each other like a pair of crazed voles." While some, such as Dax, find this exciting, others, such as Quark, find it particularly intimidating. (DS9: "Looking for par'Mach in All the Wrong Places")
Worf jokingly describes Klingon making to Wesley Crusher as involving the male reading love poetry while ducking the furniture thrown by the female. (TNG: "The Dauphin")
Jadzia Dax and Worf at a traditional Klingon wedding.
The mother of the father of the groom must approve of the prospective bride before a
wedding can take place. Martok notes that no one can be in control of who they fall in love with. (DS9: "You Are Cordially Invited")
In earlier evolutionary stages, Klingons had ablative armor, were extremely territorial, and spit venom at those who wanted to harm their mates. (TNG: "Genesis")
Because of his traditional Klingon values, Worf, in general, takes mating much more seriously than his partners do, much to his chagrin and theirs. (TNG: "The Emissary", DS9: "Penumbra"), Worf and special emmisary K'Ehleyr are involved in the only Klingon-on-Klingon mating ritual depicted in any season of Star Trek. This act resulted in the conception of Alexander (TNG: "The Emissary")