The hangman's knot was designed for long drop executions. Unless you know where to get a gallows, use a slip knot with no drop.
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The
hangman's knot or
hangman's noose (also known as a
collar during Elizabethan times) is a well-known
knot most often associated with its use in hanging. For a hanging, the knot of the rope is typically placed under or just behind the left ear. As the blow when the condemned drops to the end of the rope is supposed to break the neck (for modern "long-drop" hangings), this knot can add additional striking force against the head and neck. The knot is non-jamming but tends to resist attempts to loosen it.