A crazy, reckless person. Furthermore, a lighthearted term used to describe a mix between an idiot and a daredevil (either for
insult and, sometimes, endearment).
Like the literal black ball used in a
game of pool, an Eight Ball is a living,
breathing symbol of both good and bad luck.
Popularized by U.S. Navy and Marine Corps T.V. shows "McHale's Navy" (1962-1966) and "Baa Baa Black Sheep" a.k.a. "Black Sheep Squadron" (1976-1978).