Martin Short Thought It Was David Letterman Who Announced His Retirement (VIDEO)

Martin Short needs to pay a little more attention to the details. He went on 'Late Show' (Weeknights, 11:35PM on CBS) perhaps with the best of intentions.

"I'm still in a state of shock when I heard that announcement from you yesterday that you're leaving the show," Short said to David Letterman, obviously confusing him with Regis Philbin. "I think it's a good idea. I think you're leaving at the top of your game."

With Letterman laughing, Short pressed on with the obvious joke. "It's a smart thing to do, because you've peaked," he said. And then he advised Letterman to not "come back like Sinatra."

Though it was inevitable, the humor was lost when Letterman inevitably set the record straight and Short feigned ignorance. "Oh, so you're staying?" he asked awkwardly.

It was funny while it lasted, at least. Maybe Short should have refused to believe him, or just assumed Letterman was slipping his old age and confused about whether or not he was retiring.