If you're tired of only changing the color of your hair, you can try for a pumpkin look for fall. The compound that gives this class of vegetable pigments its name - β-carotene - when consumed in large quantities by humans, will turn them orange. [Really, but don't try this at home! It was observed clinically in Britain during WW II when food shortages led some people to include large amounts of carrots in their diets.]
If you thought the bright color of Cheez-Whiz
What does this all have to do with quantum chemistry? A very simple quantum mechanical model, the particle in a one-dimensional box, can be used to predict the color of conjugated dyes.
UPDATE: Bixin isn't used to color Cheetos, but is used in Cheez Whiz.