Star Trek: The Next Generation:
For the Klingon race the Age of Ascension is a rite of passage. It is the marking of a new level of spiritual attainment for a Klingon warrior. It is roughly equivalent to the Jewish bar mitzvah.
What is involved in this ritual:
There is a reciting by the ascendee. He proclaims: “DaHjaj Suvwl’e’jiH. tlgwlj Sa’angNIS. lw blQtlqDaq jijaH.” In English this means “Today I am a Warrior. I must show you my heart. I travel the river of blood.” After yelling this, the warrior then strides between two lines of other Klingons. Each of these Klingons subject the warrior (who is usually male) to painstiks. While this is done the warrior is expected to express his or her most profound feelings while under extreme duress.
In 2355, Worf underwent his Age of Ascension ritual. He was 15 years old at the time. Ten years later he celebrated that anniversary with his friends on the Enterprise-D. Kurn, Worf’s brother, was not told that he was the son of Mogh until 2360 when he reached his own Age of Ascension.