Nothing, it's just a trend.
I guess it means that you scrached your skin in your sleep ! and dead skin cells are that black think under your fingernails
fingernail
Sending a black feather can mean a great many things. Sometimes sending someone a black feather can mean wishing death on them.
its on the mohs scale
It means you have injured a fingernail.
It's someone with black hair.
I think you mean pints not paints? If so there are 2 cups in one pint.
A Black person is someone with dark-colored skin, especially when of African descent.
Their hair is a dark as can be. No tones of brown just dark black.
Maybe you just rock the color black!
Spell put on someone by black magic.