The singer, 48, dished all the details about her gift for Shelton during her appearance on Tuesday’s Tonight Show Starring Jimmy Fallon, explaining that it’s difficult to shop for the “hottest cowboy ever and Sexiest Man Alive.”
“He’s really hard to buy for. I think because he doesn’t fit in any of my furniture at my house, he’s too big,” said the mother of three, who teamed up with the 6’5″ Shelton on her holiday duet “You Make It Feel Like Christmas.”
“‘I’m gonna get you a couch, like, that’s gonna be your Christmas present,'” she told him. “I’m putting it outside so he can put out fires and stuff like that. I try to make him comfortable in L.A.”
As for the kind of chair, she’ll be buying for the country crooner, Stefani already knows a specific brand she will not be getting. “We’re not gonna do La-Z-Boy at my house,” she said.
Stefani and Shelton began dating in November 2015 when they met as coaches on The Voice, not long after Shelton’s divorce from fellow country crooner Miranda Lambert and Stefani’s divorce from husband Gavin Rossdale.
And for their first Christmas together in 2015, they vacationed at Shelton’s home in Tishomingo, Oklahoma, dressed in matching camouflage outfits.
WATCH: Blake Shelton Is This Year’s Sexiest Man Alive: ‘I Can’t Wait to Shove This Up Adam’s A—!’
“[He’s] somebody that is at the top of their game and talented and genuine and cool and generous and just not self-aware at all — completely a man,” Stefani told PEOPLE of why her boyfriend is the perfect choice for Sexiest Man Alive.
“He doesn’t even know how cute he is. [He]’s cocky but only because he’s a cowboy!” Stefani joked.
“It’s interesting because I don’t think any of those things like beauty or sexy or whatever way you want to describe humans is necessarily a physical thing that people are attracted to,” she said. “It’s all about the heart, and [Blake] has that big ol’ gigantic heart in there, so he’s quite an attractive human. I’m not the only one that thinks it!”
Stefani’s hour-long holiday special, You Make Me Feel Like Christmas, airs Dec. 12 on NBC.