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?