How can you have a favorite color if you are color blind?!

Color blind is a misleading term. He's most likely not fully color blind, seeing only grays. Most people deemed color blind only have deficiencies in determining certain shades of a color. I have deuteranomalous trichromacy, which is by far the most common kind. I have trouble determining some green shades, but I can still see most greens. I can tell that the bar at the top of the page is green. The other forms of color deficiency are very rare, so chances are he has the same condition as me. It's hard to explain what we see differently. If he is completely color blind, which is extremely rare, then I suppose he would be full of crap. But chances are he can see at least most colors just fine.

Maybe he's not red/greed color blind. For a better answer, ask your friend. No sense in asking strangers when you can ask a friend for his first hand experience answer.