In your new film Dinner for Schmucks, with Steve Carell and Paul Rudd, you play a macho performance artist with a penchant for nudity. Do you enjoy playing extroverts?

Yeah, it is really fun. In real life I'm very low-key. A wallflower. One of the reasons I went into comedy and acting was that I was sick of being shy. I guess I have an extrovert side and now I get to channel it.

How did you cope with the nudity?

One of the most embarrassing moments was when I was on holiday in Athens and they sent me all these references for the performance art. I checked my email at an internet cafe and opened a PDF with 20 or 30 pictures of naked guys. A lot of them were from gay porn. Some were of Colin Farrell. The studio needed one of me for the film so I had to find a photographer and say: "I'd like photos like these taken of myself, it's for a big Hollywood movie." I asked the photographer where the studio was and she said: "Studio? No studio." So I had to go to a public park in Athens and replicate gay porn pics in my underpants.

Are you excited about your new Hollywood career?

Oh, I'm totally here by accident, I never set out to do this.

It must be quite a culture shock, starting out doing small shows with Flight of the Conchords at the Edinburgh Festival and ending up in Hollywood.

The last Conchords live show we did was at the Hollywood Bowl, which is a bit different from the Gilded Balloon in Edinburgh. We would really have to bust our asses to get people along to the first Edinburgh shows, flyposting and all that stuff, which of course we don't have to do now.

How much did Britain contribute to the rise of the Conchords?

I would say, totally. If it were not for Edinburgh we probably would have quit by now, because in New Zealand you can't really survive doing comedy. When we were starting out there was a sense of the country being embarrassed by its own artistic output, by its own accent. The term we use is "cultural cringe". So it was great to go to Britain where comedy is so celebrated.

Do you get a better reception in New Zealand now?

The show is popular with certain people and everyone knows about it. It's a weird situation because people say: "Oh these guys are supposed to be good", but of course comedy, like music, doesn't appeal to everybody. So we get comments like: "Oh, it's only popular in America because Americans are idiots."

Of all the songs in Flight of the Conchords, which was the most fun to develop?

I always enjoyed "Leggy Blonde", which Rhys Darby sings in the first series. Maybe that's because I enjoy it more when I don't have to do something. We used to spend weeks writing the songs, but in the second series there would be times when we only had the afternoon before we shot it. But I quite like "Sugar Lumps". We wrote it in hardly any time, which isn't surprising if you read the lyrics. It's one of the most fun ones to do live. Everything else we play with acoustic instruments but that one we do with samplers. So much power, just by pressing a button!

You and Bret [McKenzie, Conchords co-star] have a Simpsons appearance coming up. Were you happy to be asked?

Yeah, we were over the moon. We don't play ourselves, because most people won't know who we are, but they'll look like yellow versions of ourselves. We play counsellors at an arts camp that Lisa's going to. It's pretty fun. We just went to a studio and recorded it, but, yeah, we were really flattered. I remember begging my mother to let me stay up and watch The Simpsons when it started as short sketches on The Tracey Ullman Show.

Next up, you're playing the villain in Men in Black III.

Yeah. My character's an alien, which means I have these prosthetics over my face and body. I've been travelling to the States for the last few months just to try on different prosthetics. Then I go home to New Zealand and have a totally ordinary lifestyle where I'm changing nappies [Clement has a one-year-old son, Sophocles Iraia, with his wife, playwright Miranda Manasiadis] and going to the park.

So have we seen the end of the Conchords?

There won't be any more of the TV show, but we'll still do the live thing. It might be fun to do a movie musical with a little bit of a budget. I say that just because we had so little budget on the Conchords and so little time to do the music videos, so it'd be great to be able to put a bit more thought into it.

Have you noticed you have internet fan sites? One of them is called Jemainiacs.

I haven't seen that one. What's funny about that is, it's a term I made up myself long before there were any such people. When we were doing the show in Edinburgh, we obviously didn't have any fans, so talking about having fans – female fans especially – was a hilarious joke for us and the audience. But when you've got a TV show that plays to enough people I guess there will be a certain percentage that fit into that category.

Mel was an obsessive FOTC fan in the TV series. Do you now have real-life Mels?

Oh yeah. The first people we experienced like that were Lord of the Rings fans, because Bret was in Lord of the Rings: he played a non-speaking elf. A joke fansite started around him called Figwit, which stood for: "Frodo Is Great, Who Is That?" Lord of the Rings fans would travel across Europe and even from the States to see us in Edinburgh. They would be hugely nervous, especially around Bret, which is odd when you consider how easy it is to be an extra on a film. But then we got our own fans. Often, in some of Mel's more bizarre storylines, we're quoting what people actually said. They're pretty nice, though. They send us a lot of knitted goods.

Dinner for Schmucks opens on 3 September