Widely suspected to be human flesh, no one knows exactly what it is, other than that it looks and tastes strange. The presence of the item is often used in the game to indicate that those possessing it are cannibals.
It appears to be bits of meat skewered onto a stick. It restores a small amount of Hit Points and also gives a small dose of radiation. In Fallout: New Vegas, this meat causes a -1 penalty to Strength.