Retard in one context is fine. Calling someone stupid basically. Retard in another context is totally not cool. Since I am about 110% sure my intellect is superior to yours, I felt I needed to explain that to you. In one context, it is not derogatory. In another, it most certainly is. Basically, I see it as I see the "N" word for the black community. I don't think either word is OK for either community really, but since they're in use, you may want to learn the difference between "a" and "er. Get it? Got it? Good.