Drew Parker still can't believe Brooks & Dunn are singing one of his songs. He's one of four writers on Luke Combs' "1, 2 Many," which features the legendary '90s country duo and was also written by Combs, Dan Isbell and Tyler King.

"It's incredible," Parker says with a laugh of Brooks & Dunn's inclusion on the song — almost as incredible as how it came together in the first place.

As Parker tells The Boot, the chorus of "1,2 Many" was already finished when he and Isbell met Combs out on the road for a songwriting session. They helped him finish the verses, but still needed a bridge — that's when Combs' live show inspired them.

Below, Parker shares the story behind "1, 2 Many," in his own words.

This is a funny story: The chorus of "1, 2 Many" was actually written before I ever started writing on it. Me and Dan Isbell ... Luke was out on tour, and Luke had brought me and him out, just to write that weekend ...

I think we were in Columbus, Ohio. We were sitting on the bus, and Luke's like, "Hey, man, I got this idea that I started years ago with Tyler" — who's his guitar player — "but we'd never finished it ... I have a chorus and it's just there."

And so, Luke played us the chorus [of "1, 2 Many"] ... and me and Dan looked at each other like, "This is awesome!" So me and Dan then knew it was our job, with Luke, to write the verses ...

We had gotten the verses done, and then, it was our last night out on the road, and we didn't have a bridge. And me and Dan were trying to come up with something and struggling, and I told Dan, "Let's go watch Luke's show for some inspiration, and then we'll come back and see if we can finish it."

We're standing there, side stage, watching Luke play ... and in the middle of [a] song, he would throw his drink into the crowd, and when he did that, the fans went crazy. And I'm like, "Man, we need that moment in the song."

I kept thinking, and I'm like, "Alright, I know Luke's fans love would love to challenge him to shotgun a beer" ... I told Dan, "I got it, man. Let's go back to the bus," so me and Dan went back to the bus, and I'm like, "Listen — hear me out" ...

He was like, "Man, I don't know." Me and Dan have made a joke out of this now, because he fought me on it for a minute ...

So, Luke got done playing the show, came out on the bus. I told Dan, "Just let me [suggest] it. If he hates it and you hate it, then that's fine. But I think he's gonna love it." ... And Luke goes "Oh, I love it." And Dan goes, "Man, I knew you were gonna love it!" ...

I'm a huge Brooks & Dunn fan — I mean, absolutely huge — and I'll never forget where I was the day, the moment, that I heard them singing on ["1, 2 Many"]. I mean, [it was] just an absolutely incredible moment that I'll never forget.

If you'd have told me five years ago, before I moved to Nashville, that I would write a song that Brooks & Dunn would sing on, I would call you a liar. But, I mean, anything's possible. And I'm super thankful for Luke believing in that song, and for hearing that song as we wrote it and saying, "Man, I think Brooks & Dunn would be a great thing to add to this" ... As a kid who grew up on '90s country, it just is as awesome as it gets.

[I found out Brooks & Dunn were going to sing on the song when] I was at our office, [in] downtown Nashville, and I had gotten this package in the mail, and it was addressed to me. I opened it up, and this [vintage Brooks & Dunn] hat was in the package ... About five minutes after I opened the package and had put this hat on, I got a FaceTime from Luke. And I'm showing him my hat ... and he was like, "Dude, do you already know?"

And I'm like, "What are you talking about? I just got this from somebody" ... And he was like, "Well, dude, it's so funny you just got that. I didn't send that to you ... [but] Brooks & Dunn is gonna sing on "1, 2 Many.""

And I'm like, "You're kidding me!" ... It was just a great moment of celebration for them being on it. But I was like, "I'm not holding you to it 'til I hear it — not counting on it" ...

[The first time I heard the final version of the song], I had to pull over on the side of the interstate — I was on I-65, headed to my house, and I had to pull over. I played it there and played it all the way home ...

If I could pick one other person to be on a song other than Brooks & Dunn, it'd be Keith Whitley, and all my fans know [in] how high regard I hold Keith Whitley, so that says a lot about how much I love Brooks & Dunn.

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