Gwen Stefani had to "convince" Blake Shelton to accept the Sexiest Man Alive title

She told Jimmy Fallon on 'The Tonight Show': "This is not his thing at all. I feel responsible about this.... I had to convince him."

She admitted she told Blake: "Why would you not do it?"

Meanwhile, the 'Used to Love You' singer - who has sons Kingston, 11, Zuma, nine, and Apollo, three, from her marriage to Gavin Rossdale - has decided to buy her boyfriend of two years a couch for Christmas.

Gwen came to the conclusion the furniture item would be the ideal gift for Blake to keep at her Los Angeles home because he can't fit into any of her chairs.

She explained: "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.

"[I told him] 'I'm gonna get you a couch, like, that's gonna be your Christmas present.'

"I'm putting it outside so he can put out fires and stuff like that. I try to make him comfortable in LA."

Blake, 41, recently vowed to "milk" his new title for as long as he can.

He said: "I mean, you can't be the sexiest man alive ... unless you're the sexiest man alive. I said this in the magazine when I did my interview for 'Sexiest Man Alive,' that I had been fat and ugly my whole life, and if only for one year, I get to be sexy, I am going to milk this for everything that it's worth."