In the popular imagination at least, the jawbone is part of any self-respecting shaman's tool-kit. Children are always fascinated when I tell them about the animal origins of sound I am making with my factory-produced vibraslap: the skeleton picked clean by crows or vultures and the teeth loose in the jaw.
The modern instrument was invented by Martin Cohen. Metal pins replace the teeth and a wooden box, open at one end, functions as both jaw-bone and resonating chamber. The pins strike the walls of the box to produce the sound. Actual bones are prone to breaking but this is a much stronger instrument. The really clever thing, however, was the attachment of this box to a piece of sprung steel with a wooden ball at the other end. Striking the ball makes the steel vibrate and the 'teeth' chatter, hence the alternative name of chatterbox. The sprung steel saves developing the wrist technique that would otherwise be necessary to produce the characteristic rattlesnake sound.
No doubt the sound of the jawbone would have sent shivers down the spines of our shaman's audience and it can still provide a useful, tension-inducing sound effect for film and stage. It has also become a common rhythmic ingredient in both Latin and popular music where it functions more like a guiro (scraper).
Playing technique. The best result is obtained by holding the instrument ball up by the ergonomic bend in the steel rod. Harden the palm of your other hand by by splaying the fingers and strike the wooden ball. Bouncing the ball off other surfaces is a possible alternative but may result in too much force being applied, doing nothing to improve the sound but rising injury to the vibraslap. Striking the box produces a different, some would say inferior, sound and is also likely to reduce the life expectancy of your instrument.