Though the show has a hipster-friendly vibe, with appearances from indie rockers, comic book references and sex jokes from Margaret Atwood, the show also gets attention from those "who've given up on staying in the know about what's cool or are maybe alienated by skinny jeans and tattooed baristas," Newnam said. "We get lots of mail throughout the country from people who are like, 'Thank you so much for turning me on to that.'"

Gagliano and Newnam have even reached the point where people recognize them in public, a rare form of validation in the world of radio. Once, a fan's 3-year-old son pointed to the hosts and shouted "This is your icebreaker!"

They've also received shout-outs from Gwyneth Paltrow's Web magazine Goop, and they've taken calls from publications asking for insight about how to behave at actual dinner parties. That, to the hosts, speaks to the appeal of the show. "People still have questions about how to start conversations and find things to talk about," Newnam said, "so that's kind of become our strange calling."

As the show has grown in popularity and length — in October it added Boston's WGBH-FM to its 130 stations and it typically ranks in the top-15 "society and culture" downloads in iTunes each week — the creators have added new features. "Soundtrack" has a musician provide a personal playlist. The segments are sly ways of getting guests to talk about things they would normally be reluctant to talk about or not have a chance to address in rote promotional interviews.

PHOTOS: Behind the scenes of movies and TV

"All of a sudden you have Lisa Kudrow talking about being a mom," Newnam said. "It's a fun way to get a new dimension on our guest."

A recurring theme of the "Dinner Party" is the two questions they ask each of their main guests: "What question are you tired of being asked in interviews?" and "Tell us something we don't know; it could be about you or just an interesting fact about the world."

"It's always funny when the celebrities realize halfway through that they're talking about that thing they don't like talking about," Gagliano said. For instance, it inspired Rashida Jones to talk about her father, Quincy Jones.

When this reporter threw the hosts' signature "tell us something we don't know" question at them, Gagliano hearkened back to the early 1990s, when his rock band the Smoking Pets played Lollapalooza in Pittsburgh. They were the first band to play and their set lasted 15 minutes for a crowd of 15 people. "We sold one cassette," he said. And a little-known fact about Newnam? He has a tattoo of the word "tattoo."