Fresh off her ACM Awards date night with Blake Shelton, Gwen Stefani found herself on the set of Jimmy Kimmel Live on Wednesday (April 18) to promote her brand new Las Vegas residency. But of course, her boyfriend was a topic, too — one of his exes was a big No Doubt fan!

No, not Miranda Lambert.

"He did tell me that he dated a girl for like three months that had my face plastered all over her bedroom," Stefani says, laughing about a past conversation she had with Shelton. "So, that’s kind of weird."

Stefani also talked about her and Shelton's shared love of music, but not necessarily always a love for the same kind of music. "I did make him a ska-like reggae playlist for Valentines a couple years ago," the pop-rock-ska singer says of her country star man. "He doesn’t listen to it very often."

"You would be surprised ... Blake is like a musical jukebox. He knows so much music. The one place in which we crossover is the whole yacht rock, '70s love songs. Like, when I said Bread is one of my favorite groups ever, and he was like, ‘What? I thought you were just a rock-ska girl,'" she recalls, laughing. "He didn’t know what ska was!"

Stefani stuck around Kimmel to compete against on of her biggest fans to determine how much the fan knows about the singer, mother of three and business owner. She's excited for her Las Vegas residency, too: "It’s just going to be really fun to get really girly and really theatrical and take it to a place I haven’t taken to it before. I want them to love me."

See Pictures From Blake & Gwen's ACM Awards Date