My sister and nephew are in town, visiting New York for the first time. She's a legal professional who dealt with a certain saffron-haired real estate mogul who wouldn't buy a private plane until the letters "DT" were embroidered into the upholstery. He's the proprietor of WTF Japan Seriously.

Naturally they wanted to do all the tourist things. They went to the Statue of Liberty, Museum of Natural History, Soho, Chinatown, and Little Italy. Last night we went to Times Square and watched a scruffy illegal Elmo hit on a cross-eyed Minnie Mouse.

"We're seeing Letterman tomorrow," Nephew announced.

"That's always fun," I replied. "Who are the guests going to be?"

"John Goodman and Melissa Etheridge."

I nearly choked on my giant pretzel. Poor guy, I thought. What, was Samuel Gompers busy? I mean, I love the left-wingers, but in terms of entertainment value they're right around putting your hand in ice water and watching your scrotum shrivel up.

John Goodman played a blue-collar drywall contractor in the anti-authority, poor-is-good Roseanne. He's worked with Aaron Sorkin and George Clooney, which is this century's version of entertaining migrant farmworkers with Pete Seeger. What's he going to talk about: union busting in third-world nations?

And Melissa Etheridge. Really, did anybody still listen to cruelty-free, socially-responsible music? That went out with Space Food Sticks. Had she been holed up in a sheep farm in Australia for the last ten years trying to come up with a rhyme for Pakistani?

I felt bad for my nephew, but mostly I wondered why Letterman made such a ridiculous mistake. Had he finally gone off the deep end? I mean, why on earth would they alert prospective audience members that they'll be taking hours they could be spending on the Toys R Us ferris wheel to listen to lengthy diatribes against Paul Ryan and stories about micro-lending startups in Bajnipoor? That if they aren't members of PFLAG with backyard compost heaps they'd have more fun hitting themselves with rocks?

It couldn't have been more obvious: the Letterman folks were saying that if you weren't the most rabid, die-hard Democrat, you should stay far away.

This morning I was flipping through the New York Times when I caught an odd sentence and everything became crystal clear. John Goodman and Melissa Etheridge on Letterman tonight?

Nope. His guest is President Obama.