Black cat bone

A black cat bone is a type of lucky charm used in the African American magical tradition of hoodoo. It is thought to ensure a variety of positive effects, such as invisibility, good luck, protection from malevolent magic, rebirth after death, and romantic success.

...Got a black cat bone
got a mojo too,
I got John the Conqueror root,
I'm gonna mess with you...

The bone, anointed with Van Van oil, may be carried as a component of a mojo bag; alternatively, without the coating of oil, it is held in the charm-user's mouth.

The black cat has been a symbol of both good and ill luck in near-worldwide folklore accounts. Magical traditions involving black cat bones, specifically, have been found in German-Canadian practice as well as in hoodoo; these German-Canadian magic-makers were not previously in contact with hoodooists, suggesting a European origin to the charm.

The use of the black cat bone to ensure invisibility, specifically as an aid to people, is comparable to the European Hand of Glory.

After a black cat is caught, it is almost universally boiled alive in a pot of water at midnight, so that its bones may be more easily looked over by the hoodooist. One particular bone, special to each individual cat, contains all the magical efficacy alone. A variety of rituals and methods are used to determine which bone is the right one, and preparation before the cat's slaughter can vary according to tradition.

One method of obtaining a black cat bone, described in Zora Neale Hurston's Mules and Men, involves a period of fasting before the actual catching of the animal. After the standard boiling of the cat's corpse, each bone is tasted by the hoodooist, who then selects the first bitter-tasting bone as the correct one.

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Wikipedia