Billy Gibbons has revealed that a recent meeting with John Fogerty about their joint tour quickly turned into an accidental songwriting session.

Gibbons went to Fogerty’s Los Angeles home to make arrangements for the road trip with ZZ Top, which runs across the U.S. from May 25 to June 29, and since the former Creedence Clearwater Revival frontman had a studio in the building, they decided to take advantage.

“We went straight to work,” Gibbons told Rolling Stone in a new interview. “It was an exercise in just absolute joy.” The untitled piece was created from an idea Fogerty had come up with, and they worked on it after they jammed some of their own classic tracks, including “Fortunate Son,” “Bad Moon Rising” and “Tush.”

“I’ve been wanting to kind of hook up with Billy or ZZ for a long time,” Fogerty said. “I think we’ve traded emails. I ran into him down somewhere, and I was playing and Billy was playing the next night. I had him come into my show and we did 'Sharp Dressed Man.' It was a lot of fun. He sent me a couple of emails. I think he even gave me a CD or two that he labeled 'Big Ol' Blues.' There was a whole bunch of great old songs on there. We've been trying for a while and it finally has fallen into place, which I'm delighted about.”

Watch John Fogerty and ZZ Top Perform 'Sharp Dressed Man'

As for who will start each night's show on the upcoming tour, Gibbons joked that it was all decided by a coin toss. “Who is going to start, who is going to stop and do we have to stop? That was the real question," he said. "I think it'll work out nicely. It's a collaboration experience, which I think makes a lot of sense, not only for both bands, but for the fans and followers.”

Fogerty expressed interest in playing ZZ Top’s “La Grange,” “Sleeping Bag” and “I’m Bad, I’m Nationwide,” among others, while Gibbons named “Fortunate Son” and “Down on the Corner” as CCR songs he'd like to perform onstage. “I rattled off a half a dozen titles from the heyday of Creedence," Gibbons recalled. "[Fogerty] was grinning. He said, 'You gotta remind me. I gotta re-learn all that stuff I'm supposed to already know.' I said, 'Yeah, that's the way it goes, man. We gotta get to work.'"