wobble board

Noun

 * 1) An item of exercising equipment which challenges the sportsman to balance his weight on it as it could tilt in any direction.
 * 2) A musical instrument consisting of a flat board which is held in the hands and shaken so that the board flexes in order to produce a rhythmic "whoop-whoop" noise.
 * 1) A musical instrument consisting of a flat board which is held in the hands and shaken so that the board flexes in order to produce a rhythmic "whoop-whoop" noise.

Translations

 * Danish:
 * Finnish: wobble-tasapainolauta
 * Swedish: balansbräda