The lur'kha was a ritualistic aspect of Klingon culture. Under its terms, a Klingon child who was old enough to carry a blade was considered an adult. As such, these children were sent into the night alone with their blade. Those that were destined to be warriors survived the trial.
In 2347 in the mirror universe, Worf was undergoing the lur'kha at Khitomer when the Romulans attacked. This spared him the death suffered by his family and he emerged from the trial just in time to see the Klingon Empire regain control of the planet. (DS9 novel: Dark Passions)
- It's unknown whether this ritual has a counterpart in the standard universe.