Rocker John Mellencamp ignored studio no-smoking rules during an appearance on America's The Late Show with David Letterman on Monday (27Apr15) by strolling out onstage with a lit cigarette. Host Letterman poked fun at his old pal by pretending to write down the Surgeon General's number for Mellencamp to help him quit, but he responded to the jab by explaining, "I'm only good at about three or four things; smoking is my strong suit... I figure my body is so polluted now that nothing can live in there now. Cancer would go in and say, 'I'm not going in there, there's gotta be somebody else better to go into!' So I'm just gonna keep smoking."