Rite of Ornoc
From The Stargate Omnipedia
An ancient Jaffa rite not spoken of openly, evidently pertaining to a newly married couple. Occurring on the first eve of shim'roa, a knife is required for it to be completed.
Younger Jaffa seem to regard the rite as outmoded, and no longer perform it with regularity.
KEY EPISODE
Sacrifices - When Teal'c recommends Rya'c ensure his knife is as sharp as possible for the Rite of Ornoc, Rya'c hopes to be able to do away with more of the old ways.