I do that ALL the time! I'm mixed race, so my sisters and brother are white but I've got a bit of colour, so if some one calls me, lets say " the black sheep" of family in aconversation about hobbies then it's all "ARE YOU BEING RACIST TOWARDS ME?!" It's pretty funny to watch them get all tongue tied and "No no no no!! o hgod I'm so sorry!" and feel all awkard. Of course I tell them I'm joking and have no problem with them.