Despite being banned from this year's Jimmy Kimmel Live: After The Oscars the 45-year-old managed to get smuggled in by best friend Ben Affleck only to be pushed off the stage!
The hilarious bit saw Affleck stumble on stage wearing a huge overcoat hiding Damon who was strapped to his friend with a special harness. "I hate to say it but you've ballooned," Jimmy Kimmel quipped, with Affleck, 43, responding: "Wow, I didn't know tonight was about body shaming."
Once Damon's cover was blown, Kimmel, 48, wasted no time in him getting pushed off stage in his chair. "You are ruining my Oscars show!"
With that out of the way, Affleck talked about his son Sam's superhero-themed 4th birthday party which he attended with Jennifer Garner.
Affleck revealed this his son had asked him to come dressed as the real Batman. "I was like OK," he began. "I had to call the studio and say "Is there any chance someone has the costume around?""
But the movie studio hesitated before lending out the famous cape. "They trust me for the movie but not for a four-year-old's birthday."
Once he had the costume, he then had to face the reality of putting it on off-set, at a children's birthday party. "There was Wonder Woman, Captain America, Iron Man and there was me. It was so mortifying ... I didn't think that all the kids' parents would be there. It's 11 in the morning and [the parents] are like, wow, Batman!"
Kimmel then joked with the actor that he has a deleted scene in Batman v Superman: Dawn of Justice which resulted in an epic skit with the duo, joined by Henry Cavill.