The actor was on the show to promote their new film, A Quiet Place, and the crowd erupted at the mention of Emily's name.
"That reaction means I married up, and don't I know it," he said clapping. "Please, they don't have to tell me — the customs agent in London did.
"Emily just shot a movie, it's a small indie called Mary Poppins," he joked, "And I went to visit her all the time. It was going great with all the customs experiences, but then I hit this guy who's about my age and he looked like he was about to get a little surly with me. He said 'says here you're an actor, would I know you from anything?' and I went 'you know we redid the UK version of The Office' - strike one!"
The customs agent then asked John if he was visiting anyone in London, and when he said he was visiting his wife, Emily Blunt, the man had a very rude reaction. But don't let us spoil it for you, because John's re-telling of the tale is much more impressive....
We're obsessed with these two.
Since John and Emily began their promotional press tour for the new horror film, we've been treated to plenty of interviews, each filled with gushing statements and hilarious family anecdotes.
Emily recently told the story of how the couple met during her appearance on Late Night With Seth Meyers...
She also joked about being the least-favourite parent to their daughters, Hazel and Violet, in an interview with Entertainment Tonight at the film's premiere.
"I mean, Mother's Day and any birthdays in my house are kind of funny because my kids are terrible at keeping surprises," she said. "Especially the older one, she's like, 'Mummy, I got you that pink scarf you loved.'"
Admitting a fear many parents have, Emily said, "They may like John even more than me, which is slightly upsetting at times. When I ask the little one, 'Who's your best friend?' She's like, 'Daddy.'"
Emily joked "I'm still kind of top dog, but I'm just going to have to keep him working so he's not there."
Be still, our beating hearts.