Letterman, 60, greeted Hilton telling her she looked "better than ever" as she took a seat.

After welcoming her back to New York City ("I love New York – I was born here," Hilton said), Letterman abruptly asked: "Uh, how'd you like being in jail?" Audience members gasped and laughed as Hilton, 26, paused for a few seconds before saying, "Not too much."

Letterman then observed, "You know what, they locked up your friend Nicole," referring to Nicole Richie's brief time in jail for a DUI.

About Hilton's own experience behind bars, Letterman asked: "Tell us now looking back on that experience, what have we learned? What can you tell us?" Hilton shifted in her seat before answering, "Well, obviously it was a very traumatic experience, but I did it, so I feel like I can do anything now."

After grilling her about the food – dinner, Hilton said, was normally "jail mystery meat" – Letterman kept going: "So what was it you did? Do you know what you did?" Obviously uncomfortable, Hilton stared at Letterman and laughed nervously. "It was something about driving with an invalid license, wasn't it?" Letterman said. "Yeah," Hilton answered.

David Letterman continued ...