After he successfully completed chemotherapy and radiation, and survived this scare (I still sport a yellow "LIVESTRONG" wristband in honor of him, despite the fact that they are "out of style"), he felt that the metaphor of the comedy and tragedy masks best represented his struggle.
To him, the tattoo represents life. It is a badge of survival, and a reminder of the importance of humor in the face of the most dire of circumstances. I was only on the sidelines when David struggled. But through it all, he managed to maintain a strong sense of comedy. His sense of humor took a beating, but it never gave up, and it sustained him and let him remain positive. He acknowledges that that attitude had a place in the battle for his life.
The tattoo is discreetly located on his left calf. I say discreetly, because David is not one to wear shorts. I have always seen him in slacks or jeans, but never shorts.
He doesn't recall specifically where he had this inked, other than a shop in SoHo.
Thanks, David, for sharing your tattoo!
