White crayons.

I actually don't understand why everyone says "you're about as pointless as a white crayon". WHITE CRAYONS ARE NOT POINTLESS.
White crayons work the best on black paper, better than any other crayon. Does this still make them pointless? You might have only black paper but have every colour and shade of crayon ever invented. In that situation the white crayon be your best option.
If you had a done a drawing with coloured crayons, what if it needed blending or the colour needed to be toned down or made more subtle by blending, you may need white. If you needed a colour to be lighter, white would be your best man, or woman.
WHITE CRAYONS ARE NEEDED.