Emily Blunt got on so well with her SUNSHINE CLEANING co-star Amy Adams the pair ostracised the rest of the cast during the shoot.
The actresses, who first met on the set of 2007's Charlie Wilson's War, play troubled sisters who set up their own business cleaning up hazardous crime-scenes in the new film.
The pair bonded over Mexican food and numerous shopping trips during their time making the movie.
And they enjoyed their on-set antics so much they refused to let other cast members in on their jokes because they were having so much fun on their own.
Blunt says, "I'd never had a burrito before, so I blame her for the fact I have to go to the gym more now.
"She's probably the person I've had the most fun with on a film set. She's just the best playmate I could have ever asked for because she's fearless about looking silly. I think we probably alienated other people because we found ourselves very funny."