Newly minted Dancing with the Stars contestant David Arquette was on tonight's Late Show. Arquette talked to David Letterman about being sober from alcohol, reconciling with estranged wife Courteney Cox, being enamored with fellow DWTS contestant Rob Kardashian's "great ass" (it's true, his ass is pretty spectacular), being scared of Nancy Grace, and more. But mostly, he just giggled. A lot! Check out our video of the interview's best four minutes above.