My dear friend,I have to say,I doubt there is no one want to turn the whites of eyes black,except you.what's more,that is impossible to turn whites into black.Healthy eyes got clear whites,unhealthy whites of eyes will become dull, red, and even yellow.Do not mention about black whites,which can be so horrible.
However ,if you want black whites only because you want to make fun of others,Here is my suggestion.
Close your eyes first,then draw your eyelid with black eye shadow.You'll find that it seems your eyes are entirely black every time when you close your eyes.That's funny right?
Are you serious? You sure you wanna make the whites of your eyes turn black, like a wolfman or something? So, as a matter of fact, there are simply no natural ways to achieve the desired effect you want. However, currently, on the market, there are indeed some crazy special contact lenses which could satisfy your needs. Just visit Alibaba and type in special effect contacts and you will see millions of them.
Yes, you could make the whites of your eyes become black by wearing the colored contact lenses. The circle contact lenses could make you reach such requirements. The black circle contact lenses will make your whites of the eyes become black and make your eyes look big and shining. However, you should not wear it for a long time which may cause many eyes problems for you.