You're a bit on the odd side > You are a bit " strange" of a person ( meaning he thinks the things you do are strange,unusual or unexpected because what you do or say is not what a normal person would do ). Why does he always like to eat with his hands when he is eating a steak instead of using a knife? Oh, its odd, I know. / Oh , he is a bit on the odd side . Didn't you know?

It means that you are eccentric. If the person is a friend, then hopefully it's a friendly reaction to something you did which they found strange.