Last night on The Late Show, David Letterman took Louis C.K. to task for dissing the late-night host on an episode of Louie. The quick C.K. answered, "I didn't mean you. It's this guy Jimmy Letterman." Plus: On Conan, The Walking Dead's Steven Yeun disclosed why Glenn never seems to get scruffy, a very tan Jack McBrayer made another surprise cameo, and Triumph the Insult Comic Dog insulted the Real Housewives of Atlanta to death. Also: On Late Night, Sarah Silverman observed one logic flaw in Game of Thrones; and on the Tonight Show, Max Greenfield recounted his early Hollywood years of cashing in on MTV and enjoying the money with Entourage's Jerry Ferrara. Watch our compilation to see what you missed.