John Goodman pretended to be an "a*shole actor" on set of '10 Cloverfield Lane'.
In the psychological thriller, the 63-year-old actor plays Howard Stambler, a man with "a personality disorder", who believes there has been an alien attack or Russian military offensive against America and starts holding people captive in an underground bunker.
Goodman needed to be rude to his castmates - including Mary Elizabeth Winstead and John Gallagher, Jr. - in order to master the sinister and complicated character.
Asked how he delved into the mind of Howard, he explained: "I'll try and stay, not in character, but stay with the rhythm of the piece for when we picked it up again. I tried to remain a little distance just to be an a*shole actor."
He added: "I'd never played a guy like this before. I like the idea of a survivalist facing judgement day, it was all new. It was all fresh.
"He's a lonely guy and I think he liked to put up a front, he definitely has a personality disorder, so there was a lot there, and it's a great script. With a script this good you don't have to do a lot of research."
Goodman has also revealed he had no idea the film was meant to be "a secret".
Fans were left in shock when they discovered the movie was being released just two months after its production was announced, with producer J.J. Abrams hiding the title of the film by releasing production details online under the title 'Valencia'.
But Goodman had no idea the movie - which is a sequel to 2008 monster movie 'Cloverfield' - the project was top secret when he was making it.
Talking to website HeyUGuys, Goodman said: "I didn't know it was a secret film, I hadn't thought of it that way. They asked us not to spill too much of the plot development if any because there are so many surprise twists, but I did it and moved on to other things."