While speaking with ET to promote his new movie, Free Guy, the 44-year-old actor explained why he's been a longtime fan of Carey, and what it's like being a part of her "Lambily" along with his wife, Blake Lively, and their kids, James, 6, Inez, 4, and Betty, 1.
"We are obsessives. We love Mariah," Reynolds gushed to ET's Rachel Smith. "We love music, we love celebration. I mean, that is what music is, so it just drives you into a feeling."
When asked if he considers himself part of Carey's "Lambily" -- the name she gives to her loyal fans -- Reynolds replied, "Oh yeah, for sure, in a sea of wolves."
Reynolds also told ET it was actually his idea, in fact, to incorporate Carey's hit song, "Fantasy," into Free Guy, which hits theaters Aug. 13.
"We all did rewrites of the script ... and Mariah Carey's 'Fantasy,' I put that in the script," he said. "It was like, it really beamed like an engine for the movie. And I love that Jodie Comer in the third act of the movie actually sings. The person singing in the third act is actually Jodie. A lot of other people don't realize that. I love that."
Free Guy follows a bank teller named Guy (Reynolds), who discovers he's actually a background character in a Grand Theft Auto-like open world video game. When the game and everyone he loves in it are threatened, he teams up with Molotov Girl (Comer) to save the day as the heroic Blue Shirt Guy. The film also stars Joe Keery, Lil Rel Howery, Utkarsh Ambudkar and Taika Waititi.
"I do think it's the best movie-making experience that I've ever had, easily, but also the best movie I've ever done," Reynolds previously shared, during a virtual press conference with director Shawn Levy. "It's the most pertinent to our times, in that sense. Where I feel Deadpool was a movie that was pertinent to the comic book culture when it came out, this really to me speaks in a broader spectrum of where we are in the world and how we are in the world."
Hear more in the video below.