Kidman shared the story of their failed date on the show, which involved a mutual friend setting them up at Fallon's apartment, brie cheese and video games.
"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.
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.
Watch the hilarious clip below. The awkwardness is palpable: