en made his debut as the Caped Crusader in 2016 movie Batman v Superman: Dawn of Justice, and has since appeared as the character in Suicide Squad.

His portrayal of Batman is so realistic that Samuel, Ben's youngest child with estranged wife Jennifer Garner, is certain that he actually is the superhero, and has invented a thorough back story, with the FedEx man playing a pivotal role.

The adorable tale was revealed by Ben's close friend Matt Damon as he appeared on The Late Late Show with James Corden on Thursday night (16Feb17), and told the chat show host: "That was a really sweet thing and we were like, ‘Oh that’s cute, Sam thinks he’s Batman’, but this twist that none of us saw coming was that Sam was convinced that the FedEx guy was the Joker, because it’s the same colours - the green and the purple.

"So whenever the FedEx guy comes, which is often because they get packages and scripts, it’s ‘Dad, dad, Joker, Joker!’"

Always eager to please his offspring, Ben played along with Samuel's story, and even gave the FedEx man money to join in too.

"So Ben is literally on a first name basis with this guy because he went out the first day and asked him, ‘I’ll give you twenty bucks if we pretend to fight - my kid thinks you’re the Joker!’" Matt laughed.

"And so he has to send him away every time, ‘Get out of here, Joker!’, he does the Batman voice and his kid thinks it’s the greatest thing ever."

Matt was on the show alongside Will Arnett who voices the superhero in new film The Lego Batman Movie. And when James asked the actor who he preferred in the character - Ben or Will - Matt had a diplomatic response.

"I have it on good authority that Will is actually Ben’s favourite Batman. We’re all fans of Lego Batman. I went this past weekend with my kids and it’s just awesome," he smiled.