Orange is a colour. As you haven't given any context, it's impossible to say what 'orange' means here, other than that it's meant as an insult. Perhaps the other person had a fake tan that made them look orange? Here's an example:http://www.mirror.co.uk/3am/celebrity-news/wooooops-katie-price-suffers-fake-5366762

It would be hard to know outside of the context. The first thing that I thought of was that someone was referring negatively to someone who has a fake tan. They tend to look very orange.