It turns out that Kidman and Fallon had met once before years ago but haven't seen one another since.
As these things go, the two of them have totally different memories about what happened during their meeting: Kidman thought she was going to "hang" with the star, but Fallon was totally oblivious.
"I don't know if you remember this, but we met before," Fallon told Kidman.
"Oh, I remember," Kidman replied. "Yeah, you tell your version (of the story)."
Fallon remembers walking around New York when he got a call from a friend named Rick, who tells him that Nicole Kidman wants to meet him. "Maybe to be in 'Bewitched' or something like that," Fallon recalls.
But according to Kidman, their meeting had nothing to do with a movie. "I just remember that I liked you," she tells a bewildered Fallon. "Rick, our mutual friend, says, 'oh, Jimmy wants to meet you, and you can go over to his apartment. ...' And I'm single, and I'm like, 'OK, yeah, cool.' "
Apparently, Fallon had no idea that this was supposed to be a romantic setup.
"What? Did I date Nicole Kidman?!" Fallon asked.
If he did, he didn't do it well. Kidman made her way to Fallon's apartment, only to find the comedian in "a baseball cap and, like, nothing."
"You wouldn't talk," Kidman went on. "And then you put on a video game or something, and I was like, 'this is so bad.' "
At that point in Kidman's story, Fallon fled for cover under his desk. But Kidman wasn't done: "After about an hour and a half, I thought, 'He has no interest. This is so embarrassing. And then I left and (thought), 'OK, no chemistry. Maybe he's gay?' " she said with a laugh.
Fallon swears he had "no clue at all" that he could've dated Kidman, but as the Australian actress says, it just wasn't meant to be.
Kidman went on to marry country star Keith Urban in 2006, and Fallon wed movie producer Nancy Juvonen in 2007. Both stars now have kids.
"I can't believe I dated Nicole Kidman!" Fallon said. "This is one of the most awkward moments ever."