Hosers may want to grab some Timbits, put on a cozy pair of Mukluk slippers and snuggle up with a Bay blanket for this week's episode of How I Met Your Mother — the romantic comedy is headed to Canada.

Its Canuck star Cobie Smulders says the new instalment features a parade of homegrown celebs including Geddy Lee, Steven Page and Luc Robitaille, and the return of her goofy '80s alter ego, singing sensation Robin Sparkles — who displays a much darker side than we've ever seen before.

"It's Robin's grunge days, which I am definitely more in tune with than the '80s pop stuff," Smulders reveals by phone while vacationing at the California ski area Bear Mountain.

"I feel like this is sort of at the tail end of her [music] career. It's sort of the moment that Robin says, 'You know what? I don't want to be Robin Sparkles anymore.' She's sort of breaking away from all that and she does that by becoming this character of Robin Daggers, which has a lot of similarities to Alanis Morissette."

Smulders' goofy teen-pop character has been a long-running gag on the Monday night show, allowing writers to simultaneously send-up '80s cheese and extreme Canadian stereotypes.

Sparkles generally shows up by way of off-the-wall flashbacks and jokes about the Canuck roots of Smulders's regular character on the show, TV journalist Robin Scherbatsky.

Smulders says this episode is different because Robin's fiancé Barney, played by Neil Patrick Harris, actually goes to Canada in search of his Vancouver-bred girlfriend's ex-boyfriends.

While there, he discovers revealing footage of her singing days — a Behind the Music-style TV exposé, says Smulders.

"There's just going to be a little bit of it played on the show and then I believe we're going to release [an] entire music video online somehow," she says.

"They have like a full music video. But also the tape that he finds isn't just a music video — it's like a different way to reveal Robin and her obsessive behaviour at that time."

Canadian cameos

That's where most of the cameos come in, says Smulders, also from Vancouver.

Aside from Lee, Page and Robitaille, guest stars include Alex Trebek, Alan Thicke, k.d. lang, Jason Priestley and Paul Shaffer. James Van Der Beek also returns as Robin's first boyfriend, Simon.

Smulders says the episode features a new song from Robin's past, joining a canon of campy singles that already includes Sandcastles in the Sand and Let's Go To The Mall.

"[Creators] Carter [Bays] and Craig [Thomas] wrote just such an amazing, funny but really catchy song," she says.

"They have the ability to write these songs that are ridiculous and if you listen to the lyrics they make you laugh but they also will not get out of your head — which is unfortunate sometimes but it helps us a lot."

Smulders admits to suffering some real-life ribbing for being the sole Canadian among the ensemble. She says even banal references to actual Canadian mainstays get dismissive guffaws from co-stars.

"They thought that MuchMusic was something that I made up. And I was like, 'No. It was a big deal'," Smulders says of U.S. co-stars including Josh Radnor, Jason Segel and Alyson Hannigan.

"The cast is like, 'Oh wait, that was a thing?' And I'm like, 'It was like MTV and I wanted to be a VJ, like, so bad — so badly — when I was a kid.' But they didn't believe me."

Key episode for Robin and Barney

While silly, Smulders says the Canuck-themed episode actually offers a significant leap forward in the long-standing Robin-and-Barney saga.

"It's nice to have an episode where Robin can see how invested Barney is in this relationship and he acts this way that he would never act and [see] how he's changed a little bit," she says.

She notes that their relationship is closely tied to the show's main plot driver — discovering who is the mother of the two bored teens who appear at the beginning of each episode.

Introduced in the pilot back in 2005, the kids are begrudgingly listening to their father tell them he had an incredible story for them: "The story of how I met your mother."

Past episodes have said the mystery woman will be at Robin and Barney's wedding. When that wedding actually takes place is uncertain, Smulders admits.

"We will get to the wedding, eventually," she says.

"We just got picked up for season 9 so I don't know how that works into it. I thought that at the end of this season we would be at the wedding but now I'm not so sure about the timeline of it."

The Canadian-packed episode of How I Met Your Mother airs Monday on City and CBS.