shack-shack

Etymology
Imitative of its sound.

Noun

 * 1)  A child's rattle, used in various Caribbean folk music traditions.
 * 2) A seed pod of various trees, especially, woman's tongue tree  and royal poinciana.

Usage notes
The spellings shak-shak or chac-chac may be more common in reference to the musical instrument. The seed pod may be called shack-shack in reference to the sound being like that created by the rattle.