David Letterman's retirement two months ago prompted an outpouring of tributes from multiple generations of show business fixtures, as well as President Obama. After that, he disappeared, only to resurface on Friday in Texas at Steve Martin and Martin Short's touring A Very Stupid Conversation variety show.

Here's Letterman explaining why he showed up:

I know you're asking, "What is he doing here?" I am so happy to be out of the house... [Following retirement] I had no regrets. None. I was happy. I'll make actual friends. I was complacent, I was satisfied, I was content. And then a couple of days ago Donald Trump said he was running for president. I have made the biggest mistake of my life, ladies and gentlemen.

He then delivered a Top 10 list, with some har har jokes about Trump's hair ("That's not a hairdo, it's a wind advisory!").

For a slightly more up-to-speed Trump take-down, here's Jon Stewart, who has not quite retired just yet: