You are the one that wrote of a hanging gone wrong, aren't you? The hangman's noose is designed to break the neck and sever the spinal nerve column, minimizing the trauma to the observer. In a failed hanging, with the noose too tight, the rope too tight or a noose not used, then death is by strangulation and the victim does the deadman's dance, first conciously, then unconciously and finally as the dead dance.
The deadman's dance might be characterized as flipping around on the gibbet (the crane supporting the hangman's rope), hence flibbertygibbet.
You might get some experience in what you write of rather than demonstrating my tagline...