To say Ricky Gervais is a "Simpsons" fan is to understate so wildly that it's almost not even true. His love for Homer, Marge and the people of Springfield goes miles deeper than that.

"Forget it. It's the best," says the man who created "The Office." "It's the Beatles and the Stones. It's done. Homer is the greatest comedic creation since Laurel and Hardy."

So you can imagine, he was rather flattered when "Simpsons" creator Matt Groening the producers of the FOX series asked him not just to be a guest voice on the show, but also write an episode.

"When I first got into comedy, my ambition was to get a joke on 'The Simpsons,'" Gervais says. "So writing and starring in one is ridiculous. ...

"It was the most joyous feeling of meeting your hero, and they're better than you imagined," he adds. "That was across the board -- actors, writers, directors. The spirit of 'The Simpsons' is what's kept it just the best show for 15-odd years. They don't forget why they're doing it. They're trying to be funny, trying to bring some joy into the world."

The Gervais-penned episode, airing Sunday (March 26), is called "Homer Simpson, This Is Your Wife." Over the objections of Marge, Homer signs up for a "Wife Swap"/"Trading Spouses"-style show and exchanges wives with Charles (Gervais), a guy whose wife "has married beneath herself," as Gervais puts it.

"Marge is nice to me. She's the first woman who's been nice to me in years," Gervais says. "I instantly fall in love with her and write, I think, the most excruciating love song -- if I could get in the Guinness Book of World Records for that, that would please me. It's just a dreadful, dreadful drunken attempt to woo a woman."

Gervais says he wrote the episode via e-mail conversations with executive producer Al Jean. "He did all the hard work," Gervais asserts. "I just gave him a big bag of ideas and a few scenes, then he sent it back to me -- 'Do you mean this?' ... And somehow, with his help and everyone's help, we got it into a nice, 22-minute form. I made sure I put in my favorite characters, I made sure I could write a song." He laughs. "It's like it was my special day."

Aside from the family, Gervais says his favorite Springfieldians are Moe and Lenny and Carl. And he cites "And Maggie Makes Three," in which Homer explains the circumstances of Maggie's birth and why there are no pictures of her in the house, as his favorite episode.

"He's got the one where he needs it the most, at the nuclear plant," Gervais says. "It chokes me, it honestly chokes me every time I think about it. It's just beautiful."

In addition to Sunday's "Simpsons," Gervais and writing partner Stephen Merchant are at work on season two of the showbiz satire "Extras" (which airs on HBO in this country) and an episode of "The Office" for NBC. He'll also appear in Christopher Guest's Hollywood satire "For Your Consideration" later this year and has a hugely popular podcast.

"It's ridiculous, the offers I'm getting," he says. "I've turned just about everything down the past few years" -- not because he considers himself above the material, but because he's more interested in creating his own work.

"But I couldn't turn down 'The Simpsons.' It would have been -- I dunno. A sin. It would have been a sin to turn down 'The Simpsons.'"