Ed Helms has already made us laugh as a lovable buffoon in The Office, as a toothless groom-to-be in The Hangover and now he's set to tickle our funny bone in Vacation.

Vacation is the latest instalment of the National Lampoon franchise and it looks absolutely hilarious. https://www.youtube.com/watch?v=kleG7XCqOb4 Helms plays Rusty Griswold, a role made famous by the original National Lampoon movies. Here he talks about those original films and his favourite scenes from his own movie. In playing the adult Rusty for the first time, did you go back and look at the original films to take any cues from the different actors who played the teenage Rusty? Ed Helms: I didn’t. I watched the old films just for fun and just to get in the spirit of the Griswold’s mythology, but I didn’t look for acting cues in those performances.. They’re great, but I just felt like it’s really a different character, adult Rusty. And each of those iterations of Rusty were pretty different from one another as well – they just reflect the actor portraying who Rusty was. How did you keep a straight face seeing Chris Hemsworth in the bedroom? I didn’t. [Laughs] Thankfully, the camera’s on him most of the time. It was so funny and it’s not just funny because of that prosthetic and what it looks like; it’s funny because Chris Hemsworth sold it so amazingly. I mean, he just nailed that joke with the arrogance and just walking in with all that attitude. It was amazing. Can you tell us a bit about how that scene is set up? Yeah. So, Rusty and his wife, Debbie, are visiting Audrey Griswold and she is married to an incredibly hunky cowboy, played by Chris Hemsworth, and his character’s name is Stone Crandall. So, we’re staying at their house and we’re settling down to go to bed, and Stone Crandall comes in wearing nothing but very tight underwear. Do you have a personal memory of a bad family vacation either as an adult or when you were a kid? When I was about eight, we took one family trip where we flew from Atlanta to Denver and then drove all across the western United States for two weeks in a rented Oldsmobile sedan, five of us, and there are beautiful sights in the American west: Grand Canyon, the Tetons, Four Corners, all of it. But between those are thousands of miles of bleak desert, and we almost killed each other on those drives. My brother and I got so bored we were eating grapes and we put them in the window and tried to make raisins. It didn’t work. Jonathan Goldstein and John Francis Daley wrote and make their directorial debut with this film. Do you have any trepidation when you go into a movie with first-time directors? I wasn’t prepared for just how comfortable they were as directors. That kind of blew my mind. I thought they would be nervous, that it would take maybe a week or two to kind of find their stride, but for whatever reason, they were so comfortable and confident. Having written the script, how open were they to letting you and the rest of the cast improvise on set? Any good comedy is very collaborative and those guys get that, so they were never precious about lines. The most that would happen was they would say, ‘Will you please just do one take the way we wrote it?’ And I happen to think the way they wrote it was brilliant. There are a lot of scenes where I maybe improvised a bunch, but my favourite takes were the ones on script because I just loved the language. Can you talk about working with Christina Applegate? Did you ever work with her before, and did you have that rapport right away? I met Christina, I think, at a table read for the movie a few months before we started. I’d never met her before, but we’re both a little sarcastic or something and we both kind of started making fun of each other right away, so I think that our comfort just clicked instantly. And we had a blast. She’s brilliant. I was in awe of her the whole time. She’s so effortless. In terms of how we became a family, we spent so much time in that hideous car together with the kids that we started looking out for each other and it felt like a family. Had you met Chevy Chase and Beverly D’Angelo before you shot their cameo? And what was it like coming face-to-face with the originals? No, I met them in the make-up trailer that morning and it was a dream come true for me. The original Vacation is one of a handful of movies that are the reason I do what I do. I just love those movies and that world so much, and Chevy and Beverly are a huge part of that. So, meeting them was a huge thrill and then being able to work with them and be collaborative and funny and find humor with them was incredible. Just awesome. Catch Ed Helms, Christina Applegate and Chris Hemsworth in Vacation when it reaches cinemas on August 21.