Ask Thandie Newton which of her "Run Fat Boy Run" co-stars is funnier off-camera - Simon Pegg or Hank Azaria - and Newton doesn't hesitate.
"Me," she says, and then proves it by running through the practical jokes she pulled on Pegg during production of the film, which opens Friday.
In "Run Fat Boy Run," which is "Friends" star David Schwimmer's directorial debut, Newton plays the ex-fiancée of Pegg, who abandons the pregnant Newton on their wedding day.
Five years later, she's engaged to financial wiz Azaria, who runs marathons for charity. So Pegg decides on the spur of the moment to train for a marathon and run it, hoping to win her back.
Which leaves Newton as the disapproving straight woman to Pegg's shenanigans - and Azaria as Pegg's buff foil.
"I was so starved for any comedy in the film that I was the prankster off-camera," says Newton. "Because I was not there to be funny, it provided a good distraction. Simon didn't think to watch out for me, which made him vulnerable to my fiendish plans."
THE spot for your favorite fan theories and the best Netflix recs. Learn more