Jennifer Aniston wanted to make We're the Millers ''even crazier'' by pushing the script to its limit and encouraging a full-on kissing scene.
Speaking to Total Film, she said: ''We wanted it to be pushed further. Like the scene where Emma Roberts' character is teaching Will Pouter's character to kiss. It was like, 'why not go even crazier? Have more fun and take it a step further.' So now the mum comes in and joins in.''
In the movie, Aniston (44) plays stripper Rose O'Reilly, recruited by a veteran pot dealer who creates a fake family as part of his plan to move a huge shipment of weed into the U.S. from Mexico.
Jason Sudeikis, who plays drug dealer David Clark, also made tweaks to the script to make it funnier.
'Jason was always able to bring three or four spins on any scene," says director Rawson Thurber. "His second takes would be so much funnier than anything I could have come up with.''
We're the Millers hits cinemas on August 23rd.