Kal'Hyah is the path of clarity, sometimes referred to as a "Klingon bachelor party". It is a "mental and spiritual journey" that the groom and his closest male friends take part in before the wedding. Over the course of four days, one must endure six trials: deprivation, blood, pain, sacrifice, anguish, and death. One must do this while fasting.
In 2374, prior to his marriage to Jadzia Dax, Worf underwent the Kal'Hyah in a Deep Space 9 holosuite. His companions were General Martok, Benjamin Sisko, Miles O'Brien, Julian Bashir, and Alexander Rozhenko. All but Martok were somewhat unprepared for the ritual, as they were expecting something more akin to a more traditional human bachelor party. (DS9: "You Are Cordially Invited")