When a persons neck does not break when hung, instead the muscles in the neck and back are torn. This causes the victim to spasm in agony while suffocating to death...giving the impression of dancing a crude and horrifying jigg
18th century London: One John Leech accused of murder, sentenced to hang. He prayed for a clean break but found himself dancing the Hangmans jig.
by Gallow's Humor February 28, 2011