During a visit to "Watch What Happens Live" on Monday, the actor was forced to admit he doesn't know much about his TV wife's music career, which began when Moore was a late-'90s teen pop star.
While playing a round of "Plead the Fifth" with host Andy Cohen, Ventimiglia looked startled when Cohen asked him to name three of Moore's hits — or any songs from her six studio albums.
As the crowd roared with laughter, the actor nodded his head in embarrassment.
"I think her album was called 'Candy,'" he said, getting off to an unsteady start. Though Moore's 1999 debut album was actually titled "So Real," it contained the hit single "Candy," so Cohen gave him a pass.
"And wasn't there a song called 'Crush'?" Ventimiglia rightfully guessed.
"I know she was only like 15 when she was driving the Bug," the actor recalled, referring to the lime green Volkswagen Beetle his co-star drove in the video for "Candy."
Then he gave up, shamefacedly admitting, "Oh, man, I don't know the rest. I really don't. I don't."
During the same segment, Ventimiglia was also asked to rank himself and his "This Is Us" co-stars Sterling K. Brown and Justin Hartley on a hotness scale — and, surprisingly, that proved much easier for him.
The winner? "Oh, man, Justin," the actor said immediately. "Absolutely 100 percent Justin Hartley. But Sterling K. Brown is right up there."
Added the humble star, "I'm definitely the bronze medal. I'm third place on that whole thing."
Watch all the fun high jinks in the video above!