Two forces of TV hilarity combine in a comic collision when the stars of Portlandia visit The Simpsons this week, with stars Fred Armisen and Carrie Brownstein guest-starring as a hipster couple from Portland who move to Springfield, causing Homer to emulate their oh-so-cool ways while Bart clashes with their pretentious son, T-Rex (comic Patton Oswalt).

Having the Portlandia duo on the show, explains Simpsons exec producer Matt Selman, stemmed from an idea he had to send the Simpsons on a visit to Portland — which he immediately abandoned when he saw an episode of Portlandia, the acclaimed IFC sketch-comedy series created by and starring SNL vet Armisen and musician/actress Brownstein. “It was such an amazingly smart and funny and well-observed portrait of Portland that I immediately became depressed and thought, ‘Oh well, so much for that idea…’ but then I thought, what if the Portland vibe came to Springfield…have Portlandia come to you instead of going to it.”

The Simpson’ Portland connection

As Simpsons aficionados know, the show features numerous hidden references to Portland, the boyhood hometown of series creator Matt Groening, who used various Portland street names for the show’s characters. “Ever since I’ve been going there, people have sort of pointed me in the direction of the stuff that Matt Groening incorporated into the show, you know, like Lovejoy and Burnside and everything,” says Armisen. “I still get a little thrill every time I see those things and I’m like, ‘Oh wow, that’s totally The Simpsons.’ That’s where it all comes from.”

For Armisen, there was no hesitation when it came to accepting an invitation to appear on The Simpsons. “I’ve been a fan of The Simpsons — who hasn’t been a fan of The Simpsons forever?” he says. “I was so blown away that we were even asked to do it at all. Then the more we kept finding out about the script and reading it, it was just even better because it was so funny and so good.”

Brownstein, also a long-time fan, admits to being “very excited and flattered…we were very humbled and star-struck by getting to be in the same room as Dan [Castellaneta, who voices Homer]. We kept turning to each other and just being like, ‘I have a scene with Marge!’ It was very surreal.”

Fred and Carrie’s favourite episodes

Armisen also reveals some of his favourite Simpsons moments from the past: “All the Halloween [“Treehouse of Horror”] ones are amazing,” he says. “When Jeff Goldblum’s character has to do the Planet of the Apes musical…there’s one where Homer has this really spicy chili and he goes on a trip — I think Johnny Cash is in it.”

Brownstein’s favourite: “When Homer gives Moe an idea for a new drink and he becomes rich and famous. I love that one!”

As for the plot of this week’s episode — titled “The Day the Earth Stood Cool”— Homer bonds with Portland hipster Terence (Armison) over their love of artisanal donuts, while Marge’s insecurity over bottle-feeding Maggie leads her to Terence’s significant other, Emily (Brownstein), a breastfeeding advocate. So pleased is Selman with the way the episode turned out, he quips, “We should bring Fred and Carrie back for another episode…I’d be honoured if you’d come back in some fashion.”

“A repeat character on The Simpsons?” responds Armisen? “Forget it, that’s the best!”

“We’re already saying yes!” says Brownstein of Selman’s open invitation. “We’re saying yes right now.”

 “The Day the Earth Stood Cool” episode of THE SIMPSONS airs Sunday, December 9 on Global and Fox