Chris Hemsworth probably isn’t used to being offered fitness advice by teenagers, but his Vacation co-star Skyler Gisondo decided to break the ice by offering to coach him at the gym.

“The first thing I said to him – I went up to Chris and I said, ‘If you want to get in the gym a couple days before we start rolling I can show you some good tips, how to bulk up a little bit’,” the 19-year-old revealed.

Thankfully, Avengers star Chris – who has an impressive six-pack – got the joke: “He just cracked up and I realised right away he’s just the nicest dude.”

The cast of The Vacation
The cast of Vacation (Chris Pizzello/AP)

Night At The Museum actor Skyler stars as James, the teenage son of the Griswold family, who travel across America on a disastrous road trip where everything goes spectacularly wrong.

Ed Helms and Christina Applegate play Mr and Mrs Griswold – and they were happy to embrace the comedy, no matter how undignified.

“Working in comedy movies, modesty and dignity have no place,” Ed explained. “They are useless. So I have no standards. I will do anything for a laugh.”

“I’m not precious either. We swam in poop for this movie,” Christina added.

According to Christina, this is no remake of the original 1983 film, National Lampoon’s Vacation.

“It’s really hard to convince people that this isn’t a remake or a reboot or a re-do, or us thinking we can do anything better,” she said. “This is an homage, we’re like a distant cousin.

“We get to do this cool original story that is unique unto itself.”

Luckily, original stars Chevy Chase (Clarke Griswold) and Beverly D’Angelo (Helen Griswold) are in the new film, which “took a lot of pressure off”, Christina explained.

“We kind of realised, we get to create these characters from scratch,” Ed added. “They’re brand new characters, we’re not recreating Clarke and Helen.”

Vacation is released in UK cinemas on August 21, 2015.