Crotchety Letterman tangles with Bieber about new tattoo

Justin Bieber's new tattoo hasn't made David Letterman's Top 10 list. The "Late Show" host gave the singer a stern talking-to Thursday when he spotted the fresh ink on Bieb's arm celebrating the release of his new album, "Believe." "Honestly, how does that help how you look to have a tattoo?" Letterman asked. Bieber shot back, "How does it not? It doesn't not help the way I look." The (mock?) testy exchange got physical when the host grabbed at the tat, but the heartthrob took it in stride, dismissing Letterman's lecture with a lighthearted "Grandpas." The teen sensation did promise not to decorate his arms so much that they look like the "Sixteenth Chapel."