Azizi, I did that without the excuse of having a birthday in December. I got tired of all the "Yer 29, sure, hurr-hurr-hurr" jokes when I was twenty-nine, so anyone who asked got told I was thirty. Then, when my birthday came around, I'd said it so often I'd forgotten, and thought I was thirty-one. It was another year before I figured it out, and then only because a close friend said "You can't be that old, we were born the same year!"