Astronomers call an object's reflectivity or shininess its albedo. If an object reflects none of the light that's shined on it, its albedo is 0. If an object reflects all of the light that's shined on it, its albedo it 1.
A lot of people think the moon is super reflective, but it only has an albedo of 0.12. Earth's albedo is 0.39, so Earth is more than 3x as reflective as the moon.
@mylesbkeating, objects with an albedo of 0 are called blackbodies. They're theoretical objects that absorb all radiation and then re-emit in a different form, like heat. There are no true blackbodies in nature, but a lot of things can be approximated as blackbodies.
Are there things that are not black holes that have an albedo of absolutely 0?