Taylor Swift got Prince William 'out of his shell,' according to Travis Kelce

Leave it to Taylor Swift to get the future king of the United Kingdom "out of his shell."

The singer's boyfriend, Travis Kelce, shared all the details of Swift and his not-so-secretive meeting backstage with Prince William and his children at her Eras Tour stop in London on Sunday. 

"We don't even know if we're allowed to tell you guys, but we're gonna say it here," Travis declared on his podcast "New Heights" that he hosts with brother and former NFL center, Jason Kelce.

TAYLOR SWIFT JOINED ON STAGE BY TRAVIS KELCE IN SURPRISE APPEARANCE AT LONDON ERAS TOUR STOP

"We've gotten mixed messages on whether we're allowed to share this story or not," Jason admitted.

"I might hold the trump card, but we're gonna find out. We met royalty," Travis continued. "There was royalty at the show. I was fortunate enough that I didn't get caught in traffic long enough to where I got there early and got to meet Prince William. How about that! Your royal highness, Prince William!"

Prince William shared on his own social media that he and his two eldest children, Prince George, 10 and Princess Charlotte, 9, met Swift at her Eras Tour show in London.

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"He was the coolest motherf---ing – he was so cool," Travis said of the royal, 42. "We're backstage meeting him because he was there with little George and Charlotte, and they were an absolute delight to meet. Wasn't sure if I was supposed to bow to them, curtsy, just be an American idiot and shake their hands," he joked. "We wanted to be polite."

Jason clarified that since it wasn't an official royal event, a bow or curtsy was unnecessary.

WATCH: PRINCE WILLIAM SPOTTED DANCING WHILE AT THE ‘ERAS TOUR’ IN LONDON

"I've never felt emasculated, and I did. That's the closest I've ever been," Jason continued of meeting the prince. "They were wonderful people. And that's what it's about. Obviously, literally part of a monarchy royalty. Hard to be a down-to-earth human being I would assume, but came off that way completely."

Although the Kelce brothers were meeting the prince for the first time, Swift had an established relationship with the heir to the throne. Travis explained to his brother that Swift and the Prince of Wales were already familiar with one another, having met years prior at the 2013 Winter Whites Gala held in London.

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"They actually performed karaoke with [Jon] Bon Jovi," Travis explained. "‘Livin On a Prayer’ was a song that I guess Prince William… loves to sing karaoke to. So Bon Jovi called him up and was like, 'Yo, why don't you come up here and sing this one with me.' And I guess he was like ‘I don’t know.' And Taylor was just like, ‘Let’s do this. I'll roll up there with you. You won't be the only one.'"

"So Tay got him out of his shell and sure enough he went up there and they ripped it, and they said he had a blast and I'm just like, I don't know if any other prince is doing that. You know what I mean? In terms of royalty… It seems like they like to sit back and the show is the show, but he was cool enough to be a part of it. But that just shows you how personable he is."

"Shoutout to Bon Jovi for calling the prince."

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Travis also gave Prince William his own shoutout, lauding the royal for his exceptional parenting.

"I got to say Prince William was fantastic, but the highlight was Princess Charlotte. Prince George was great too. She was so f---ing adorable," Jason first said of Kate Middleton and Prince William's middle child and only daughter.

"She was a superstar," Travis agreed. "I love it when parents ask their kids to be present, be vocal… Such a good parent move, you know what I mean? Just a good meet and a picture and to keep it moving, no. Listen, let ‘em have a moment, let ’em feel comfortable in talking to people. There's nothing worse than a f---ing  kid just walking in and just being –"

Jason interjected, "Let's not s--- on kids, here."

"No, I'm s---ing on parents not encouraging their kids to do that, that's what I'm doing. If anybody's doing it right, Prince William's doing it right. So thank you, your royal highness. It was awesome meeting you…. and Charlotte and George."