As the farewell to David Letterman tour continues, Howard Stern joined the show to weigh in on Dave's career and talked about his first appearance on the show and who his favorite guests were. But before he left, he tried to stir up trouble just one last time with Letterman by bringing up Jay Leno. See the reaction by Dave and the explanation as to why Leno won't appear on the show's final episode. I love Howard Stern. I love that he brought this up too. Interesting stuff. Check it out: