Memo to guys: Pay attention to your house guests!

Jimmy Fallon appeared gobsmacked on Tuesday night's "Tonight Show" as Nicole Kidman recalled their first disastrous meeting, which apparently occurred in the early aughts after the actress' 2001 divorce from Tom Cruise.

Brought to his NYC apartment by a mutual friend and hoping sparks might fly, Kidman described finding an oblivious, dweeby Fallon, garbed in sweatpants and a baseball cap, who played video games while she was there and "didn't talk."

"After about an hour and half, I thought, 'he has NO interest. This is so embarrassing,'" recounted Kidman, 47, who married Keith Urban in 2006. After leaving Fallon's apartment and reflecting on the lack of chemistry, she mused, "maybe he's gay."

"I had no clue at all!" protested Fallon, 40, who had earlier recounted that their mutual friend suggested bringing Kidman over because there might be a part for him in Kidman's 2005 movie, "Bewitched." While Fallon boasted of having procured Brie and saltines in anticipation of Kidman's arrival, the superstar recalled him serving corn chips and "some old Chinese food."

Fallon, married to producer Nancy Juvonen since 2007, belatedly warmed to the idea of Kidman's one-time romantic interest.

"I can't believe I dated Nicole Kidman! This is fantastic!" he crowed.

"You DIDN'T," corrected Kidman, who vainly tried to steer their chat to the new movie she was on air to promote, "Paddington."

As members of The Roots shook their heads and played "wah wah" music, Fallon attempted to present a less dorky self, brandishing his wedding ring: "You feel a little chemistry now but it's too late, baby! The ship has sailed -- OK, Nicole? Taken! I'm taken!"