Psychologically, it's our mood that effects the colors we wear. Your son has learned what most of us never really do: That certain moods end up reflecting the colors and even styles of clothes we wear. The flip side is that by recognizing this, we can use inward conditioning to "trick" ourselves into better moods. When your son is in a good mood, he tends to wear orange, so, if he knows that he's not feeling that great, he wears orange on purpose, to get himself into a better mood. Good for him!