Garner and Affleck's 4-year-old son, Samuel, is already a fan of his Dark Knight dad.
"He knows that I am Batman. It's a mixed blessing," he joked. "He also thinks that for some reason -- I don't know if it's the color combination or whatever -- that the FedEx guy is the Joker. Whenever there's a FedEx delivery, he's like, 'Dad, the Joker's outside.' The burden's on me to go out there and give the guy an extra $20 to pantomime a whole Adam West Kung Fu battle."