The radio stunt that left Carrie Bickmore in a puddle of her own (happy) tears.

What do you get when you put one of the world’s most famous musicians in the living room of one of their biggest fans?

This.

You get this:

Carrie Bickmore was the pawn in one of the most brilliant radio stunts of the year - it is only January,we know, but it's still good - after turning up to her home to discover a little 'party' was there.

A video posted to the Carrie and Tommy Show's Facebook page shows Bickmore's production team and co-host Tommy Little waiting for her in her home, predictably yelling "surprise!" as she walked in.

"Surprise what?! It's not my birthday," she said.

"You didn't get to have a party at your house last year, so we thought we would make it up to you and give you the best party ever," Little said.

"We also got you a present, and you only get it for a short amount of time.

"You have four minutes in that room."

In that room, of course, was none other than internationally-acclaimed singer/songwriter Sam Smith.

Bickmore opened the door, let out a blood-curdling scream and ran into her laundry to hide. Hyper-ventilating, Little told her to go and, um, talk to her very famous guest.

"I can't!"

LISTEN: Carrie Bickmore speaks about separating her private life from the public eye, on I Don't Know How he Does It. Post continues...

She then did, but not before acknowledging there was a tiny chance any of her words would be coherent:

"I sound like a loser!"

"Now what happens, do I have to talk to you?"

"Oh my god, you're in my house, do you like my house?"

"You're going to do have to do the talking because I am too emotional."

Smith was humbled.

"Aw, that's the best reaction ever," he said.

Later posting about the stunt on Instagram, Bickmore said it's a moment she's not forgetting quickly.

"I will never forget this moment. Sam Smith in my living room. Sam Smith thank you for being everything I thought you would be. (No idea why I hid in the laundry.)"