I have a red-headed stepchild. I thank all the powers that be (and any that don't be, just to be safe) that I have never heard this phrase before. I hope he (my red-headed stepshild) hasn't heard it either!

...this being Australia, he gets strangers calling him Bluey. Apparently this is also the reasoning behind the 'Virgin Blue' brand in Australia - Branson's Virgin is associated with red and the Aussies call red things blue. (I'd better go before I get really confused! )