In the third season of IFC’s lovably quirky sketch comedy series, Portlandia, Fred Armisen showed off his impersonation of legendary Dead Kennedys singer Jello Biafra in a sketch lampooning the idea of a punk musicians’ home becoming a historic landmark.

In Portlandia’s fourth season, which premieres Thursday, Jello Biafra himself appears in a sketch. As a man who awakes from a coma after almost two decades to discover everyone is a yuppie now. He’s pictured above with Armisen and Carrie Brownstein, plus Kim Gordon of Sonic Youth, during taping of the sketch (which kicks off episode 404, “Pull-Out King”).

At a conversation Tuesday night at 92Y with Ophira Eisenberg, Armisen and Brownstein said Biafra was more serious about his guest-starring role, unlike most of the stars who get silly with the comedy duo in Oregon’s most populous city each summer.

“He didn’t want to improvise,” Armisen said, noting that Biafra would ask the cast/crew instead for specific direction: “‘Tell me what to do. Tell me what my lines are.'” Brownstein added: “He wanted a lot of feedback. He wanted to know what his motivation was.” “I felt like such a non-pro by how much of a pro he was,” Armisen said.

Other guest stars — this season’s coterie of cameos includes appearances by Steve Buscemi, Vanessa Bayer, Jeff Goldblum, Olivia Wilde, Kirsten Dunst, Kumail Nanjiani, Duff McKagan, Maya Rudolph, Jeff Tweedy, Gus Van Sant, Paul Allen and the Portland Trail Blazers, Dan Savage, Josh Homme, Ed Begley Jr., Jason Sudeikis, k.d. lang, and Kyle MacLachlan is back as the fictional mayor.

Here’s a clip from the season premiere with Vanessa Bayer as a bank teller giving Fred and Carrie’s characters Doug and Claire their options regarding shared finances.

Most of the guest stars fit neatly within the sensibilities of Armisen and Brownstein already. “I think they treat it as a vacation in Portland,” Armisen said, “but they also come very prepared.” Brownstein said Tim Robbins brought the wig he wore from 2000’s High Fidelity and also wanted his character to sport an accent. “OK?”

At one point Tuesday night, Armisen wondered aloud: “Why isn’t there sketch drama?” “I feel like (The Celery Incident) is,” Brownstein replied. “It’s sketch noir.”

“The Celery Incident” is a series of vignettes featuring Buscemi that IFC released online in one full video.

Musician such as Aimee Mann and Sarah McLachlan have joined Brownstein in proving musicians can take a joke. In addition to Biafra, this season we’ll see Jeff Tweedy, Josh Homme and k.d. lang. The latter of which, Brownstein teases, will find herself in a love affair with a bus driver. Spoiler alert!? “It’s really sexy, and really weird.”

Armisen and Brownstein said that while they and the other three writers prepare full scripts, they do enjoy improvising, and director Jonathan Krisel will keep the cameras rolling to capture whatever may happen in the moment. “We are able to surprise ourselves, and it helps create this energy,” Brownstein said.

Speaking of which, the wigs and costumes — the award-winning costumes (Emmy Awards in 2011 and 2013) — help set the mood for the duo as they settle into so many different characters. “Sometimes you need a shorthand,” Brownstein said. Feeling a particular fabric in an outfit or putting on a wig can help them find their voices, so to speak. Brownstein said her favorite wig is that of Toni, from the feminist bookstore. “I feel very bewitching in it,” she said. “There’s a moment where I have just the wig on and no shirt…in a freezing cold river.” So look for that. “It’s one of the hair designers from SNL, so they take real care to make it look real,” Armisen said. And in real-life Portland, Ore., he noted: “Gray is OK there. So they just let it go.”

It’s well known by now how great the relationships are between Armisen and Brownstein with IFC, the show with the city, and even the duo’s friendship. Even if they still debate when they actually became friends and not just acquaintances. “No. It was 2003,” Brownstein said. “Let’s debate it right now,” Armisen quipped again Tuesday night at 92Y.

Armisen said IFC has been easy to work since the duo and Broadway Video first pitched the network. “It was their idea that we shoot the pilot there. ‘You should just make it about Portland.’ We didn’t have a title yet,” he said. Aside from a network note to figure out how to put a Subaru into a scene here and there, there’s not much interference. And as for that bookstore, In Other Words, portrayed onscreen as “Women & Women First,” Brownstein said, “We turned one of the last independent feminist bookstores in the nation into a tourist destination. That’s one of the things I’m most proud of.”

What’s the secret to their long-lasting success?

“I think we’re very protective of what we have,” Brownstein said. “We really work to keep our friendship intact….we get away from this and participate in other aspects of our lives and then we come back and we’re refreshed.”

There may not be a specific six-seasons-and-a-movie plan for Portlandia, but Armisen and Brownstein do look forward to continuing to work together beyond 2014.

“I do think we want to expand what we do together,” Brownstein said. “We just haven’t figured out what that is yet.”

IFC’s Portlandia returns for its fourth season, Feb. 27, 2014.