The "Jessica Jones" actress appeared on the long-running game show on Monday, alongside Sarah Levy from "Schitt's Creek" and designer Christian Siriano ... when they were confronted with the seemingly simple puzzle.

The category was "Family" ... and as the letters nearly filled the entire puzzle, it was clear Ritter wasn't hip to the NFL's most famous siblings.

"Uhhhhh if you're still in trouble here, go ahead and spin," a perplexed Pat Sajak told Ritter, with only two letters remaining (the "K" and "C" in "KELCE")

Credit to Ritter, despite not knowing their names, she was still able to fill in the full puzzle ... although when it came time to solve, Krysten mispronounced the fellas' last name.

"Travis and Jason Kels," Ritter said, admitting what we all knew ... "I don't know who they are."

For what it's worth, The Wheel judges were in a forgiving mood, and they gave Krysten the win despite flubbing the last name.

Levy explained to Ritter that J and T were football players ... and one of 'em is Taylor Swift's boyfriend.

"It's the Taylor Swift thing. Sadly, it's the only reason why I know who [they are]. Is it Travis Kelce? One plays for the Chiefs."

Fans of the show were shocked by what happened, and they roasted Ritter for it.

"Are they kidding all three didn’t know who they were lol! Please!" one commented.

Aside from dating one of the most famous women in the world, Travis, along with bro Jason, are Super Bowl champions with one of the biggest podcasts in the world.

More importantly, Krysten, playing for St. Jude's Children's Research Hospital, won $48,250 for charity!