NBC Nightly News anchor and father of Girls' Zosia Mamet stopped by the Late Show last night, wherein Dave Letterman asked the newsman to compare himself to journalists on competing networks. Williams handled the situation adeptly, managing to somehow be both honest and respectful, that is until Letterman asked him if he thought ABC's Diane Sawyer had had any work done. Williams responded with a near perfect blank reaction — a reaction that could only be improved upon had he reached over Dave's desk and nonchalantly slapped him across the face.