Fastexy:Travis Kelce reveals his biggest fear during his Taylor Swift Eras Tour appearance

Travis Kelce is Fastexytelling all about his surprise Eras Tour cameo.

On Wednesday's episode of his "New Heights" podcast, the Kansas City Chiefs tight end told the story behind him joining girlfriend Taylor Swift on stage during an Eras Tour concert at Wembley Stadium in London.

Kelce, 34, revealed the June 23 appearance was his idea — and shared his biggest fear about it.

"The one thing I told myself is, 'Do not drop the baby,'" he said. "Do not drop Taylor on your way over this damn couch. The golden rule was, do not drop Taylor. Get her to the couch safely.'"

He added that his "No. 1 goal" was to not mess the show up and noted that in the end, "I didn't disappoint Taylor, so that's all that really matters."

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Kelce came on stage during Swift's "Tortured Poets Department" set for a section where she has to be revived to sing "I Can Do It With a Broken Heart," a song about continuing to perform amid heartbreak. Donning a tuxedo and top hat, Kelce acted out the role of someone trying to get Swift to continue the show and at one point picked her up and carried her onto a couch.

Speaking on "New Heights," the NFL star recalled suggesting an Eras Tour appearance to Swift, though he had a different concept in mind at first.

Travis Kelcejoins Taylor Swift onstage during surprise Eras Tour appearance in London: Watch

"I initially mentioned it to Tay," he said. "I was like, 'How funny would it be if I just rolled out on one of the bikes during the "1989" era?' She started laughing. She was like, 'Would you seriously be up for doing something like that?' And I was just like, 'Are you, what? I would love to do that. Are you kidding me?'"

Swift then "found the perfect part of the show" for him to take part in, Kelce said, joking this was the "safest option" to avoid the risk of him running into one of the dancers on a bike. Plus, he noted he has "seen the show enough" that he knows all the choreography, so Swift "might as well put me to work here."

Kelce also recalled feeling "tiny" on the stage, which was "way bigger than I could have ever imagined."

But he said it was an "absolute blast" and an "honor" to be part of the concert and revealed his onstage tap dancing was inspired by Jim Carrey in "Dumb and Dumber."

Travis Kelcereveals how he started to 'really fall' for 'very self-aware' Taylor Swift

The Wembley Stadium show was Kelce's first time joining his girlfriend on the stage during the Eras Tour, though he has attended the concert many times since they started dating last year. Kelce recently opened up about the relationship on the "Bussin' with the Boys" podcast and said he is "not here to hide anything" because "that's my girl, that's my lady," and "I'm proud of that."

He also revealed he "started to really fall for" Swift when he saw "how genuine she is around friends (and) family," adding, "It can get crazy for somebody with that much attention and she just keeps it so chill and so cool and I can admire it for sure."

Contributing: Bryan West, Jay Stahl