The gift/abilty of being able to tell what ethnic background a person is from, simply by looking at them.
Mary: "Peter, what country are you from again?"
Veronica: "Why, he's half Italian, half Salvadorian, with a little bit of Irish."
Peter: "How could you have known that?"
Veronica: "I am a tank; I have awesome racedar, duh."
Radar for race issues, allowing one to sense a racist, racism, etc, in their immediate vicinity. Sometimes this racedar can be all wrong, but sometimes right on. Usually physically manifests itself as a "gut feeling".
My racedar told me that when the White guy in the truck with the Confederate flag on the back called me his "Nigga" he did not mean "friend".