Animal question. What is a "hoo-doo"? I first heard the term in a song about thirty years ago. ?

Hoodoo can be either a certain system of folk magic or a practitioner of that type of magic, according to the site below: a conjure man/woman, a root doctor. I have also heard the term used loosely to mean something akin to the "ghosties and ghoulies and long-legged beasties, and things that go bump in the night."