Hegh'bat

From Memory Alpha, the free Star Trek reference.

The hegh'bat is the Klingon ritual suicide. Tradition dictates that a close friend, or eldest son must assist. That person's role is to hand the dying Klingon a knife so that he can plunge it into his heart. The helper then removes it and then wipes the blood off on their sleeve. (TNG: "Ethics"; DS9: "Sons of Mogh")