Bret McKenzie has a problem. He's trying to figure out how to hide two grown men inside a bathtub. Which ordinarily wouldn't be too much of a problem - you'd think, anyway - only this bathtub is going to be in full view of more than 2000 people and if just one of them sees the hiding men it will be a catastrophic failure.
"These are my favourite kind of problems," he laughs.
It's a predicament that begs the question, why is he trying to hide two men inside a bathtub?
"I'm trying to get a bath built so we can get Bert and Ernie to perform Rubber Duckie," he explains. "But trying to figure that out ... you need to build a bath, but the bath needs to be able to hide a couple of dudes inside the bath. It's a pretty good problem for a working day."
Let's hope he works it out because right now McKenzie is working away on what can only be described as one of the coolest projects ever; The Jim Henson Retrospectacle in Concert.
"It's going to be a big concert," he grins. "A big, symphonic Muppet extravaganza."
He's not kidding. Running during the April school holidays, the concert is just one part of the larger Jim Henson Retrospectacle, a festival celebrating the life of Muppets creator and performer Jim Henson. Wellington's Embassy Theatre will be screening classic Muppet movies on the big screen, Te Papa will put on a Muppet-making workshops and there will be Q&A sessions with original Muppet performers.
All pretty cool, yes, but the main attraction, the headline act, the reason to book flights, hotels and get your ass down to Wellington is the live concert that McKenzie is currently working on and will perform in.
"It's the kind of show I would take my family to," he says. "I've got kids and there aren't that many live events that I get excited about taking the kids to. This will be a pretty rad experience."
Along with fan favourites from The Muppet Show, McKenzie is also bringing over characters from Sesame Street and Fraggle Rock to perform live onstage in a concert that he promises will be packed with all of their classic hits.
We're talking Rainbow Connection, People in the Neighbourhood, Being Green, Mah Na Mah Na as well as his own Muppet classics, Life's a Happy Song and his Academy Award-winning Man or Muppet.
And, if he can work out how to hide two men in a bathtub, the aforementioned Rubber Duckie.
He also promises a few surprises, "a couple of rare deep cuts for the hardcore Muppet fans moshing at the front".
Talking with him his passion for the project is palpable. And understandable.
"It's awesome that it's actually happening. It's cool, man. The Muppets have got a great energy about them. They're so fun. I can't wait to have Kermit on stage in the Michael Fowler Centre. It's going to be great."
He explains that it's been a long time, and a lot of work, to get the Retrospectacle happening. He's been working on the project with his good friend Nicola Marshall, the brains behind Wellington's Children's Film Festival, for years.
"She had the idea to do a Jim Henson Children's Film Festival, and then we thought it would be fun to do a concert," he says. "Originally it was just me with the NZSO, we thought I could do some songs. Then we thought about guests and thought wouldn't it be great to bring the Muppets out ... I've always wanted to do something live with the Muppets. And it just got bigger and bigger."
Now that's it's all systems go he's buzzing with ideas of how to make the Retrospectacle gigs the biggest damn spectacles he can.
"I'm trying to convince Gonzo to do some sort of stunt routine," he enthuses. "I'm trying to get Animal to do some timpani work. Statler and Waldorf, the two old guys, they'll be there criticising us. And then, you know, the Count, Grover …"
This happens regularly throughout our chat, while talking about the show the line between what's real and what's not blurs. Even though he's writing the show McKenzie will often say he's "asking", say, Miss Piggy, to do something as opposed to saying she's going to do it. He may be behind the curtain - or under the stage, if you prefer - but they're as real to him as they are to everyone who grew up watching The Muppets on TV.
"There's a weird thing that happens, even when you can see the puppeteer because sometimes they're just standing there, they're not hidden, but weirdly you stop looking at the person doing it and you just get drawn into the character and forget that there's a person standing there operating them," he says. "It's pretty magical."
Having worked on the two recent Muppet movies, the Retrospectacle marks McKenzie's third collaboration with the gang. It feels like he's become the go-to Muppet guy.
"I know," he beams. "I'm weirdly part of the family now. That's what's slightly different about this project, I know them."
And then the line blurs again as he explains, "It's not like I'm excited to work with them. It's more like, 'Cool, I'm gonna get together with Kermit, it's gonna be good. We'll do some work'. I haven't worked with the Sesame Street characters before, so that will be cool."
Then he catches himself and laughs, "Actually it's the same people operating them. So I have worked with them."
Along with choosing all the songs ("that's the power I wield," he jokes) he's also writing what he calls the "bits and pieces" of the show with Muppets writer Craig Sherman. The gig is mostly song-focused but there's a very loose narrative threading through.
"It's a tribute to Jim Henson's work, but the characters are not aware of who Jim Henson is," McKenzie says. "They can't talk about Jim Henson. That's one of the Muppet rules. They can't acknowledge that they're puppets. They're not allowed to."
So, as far as they're concerned they're all down here in New Zealand celebrating ... some guy?
"They won't know what I'm talking about," he laughs. "It feels like it's going to be a bit like a Flight of the Conchords show with Muppets. It reminds me of that. But Kermit will be doing Jemaine's part."
All the Muppet performers are coming over, including Dave Goelz, the last of the original Muppeteers who performs Gonzo among others, and composer and arranger Chris Caswell, who has orchestrated all the Muppet music since the beginning.
"He just knows how to make things sound Muppety," McKenzie explains. "Part of the reason I think we had a lot of success with the films was making the songs sound like they were in the world of the Muppets. Caswell knows how to get that sound because he was one of the original guys that did it. He's going to lead the band and play piano for the concerts which is going to be brilliant."
"He's literally like a character from [The Muppet Show band] The Electric Mayhem," he says cracking up.
Which brings us to the music. The New Zealand Symphony Orchestra are onboard and McKenzie is also currently assembling a crack band out of Wellington's finest players, "because a lot of their songs are band-driven," he says.
The show is shaping up to be absolutely amazing. It's also going to necessitate a trip to the Capital.
"Logistically, it's a very complex operation," he says when asked about the possibility of some Auckland shows. "It's not a particularly viable touring entity because there's an orchestra, a choir, a whole lot of Muppets, a whole lot of puppets, there's a lot of things involved. It's more of a rare experience."
"It's been a challenging process to co-ordinate because there's so many different people involved. But it is pretty exciting because the Muppets don't perform live very often. It takes a bit of effort to get that to happen."
His enthusiasm for the show is contagious and he's absolutely fizzing with ideas.
"It's going to be super-fun. I can't wait. Oh! What about the Swedish chef making a pavlova? That would be good," he says out of nowhere at one point. "Anyway …"
He's currently in full production mode, writing and planning and struggling with hiding men in bathtubs. So the final question has to be; right now is he feeling more man or Muppet?
"Definitely more man," he grins, before adding, "but I'll probably veer more Muppet as it develops."
WHO: Bret McKenzie
WHAT: The Jim Henson Retrospectacle in Concert
WHEN: April 27-28 in Wellington. Tickets onsale next Thursday via ticketmaster.