Ben's younger brother Casey took home the Best Actor prize on Sunday night (08Jan17) for his role in Manchester by the Sea and he reeled off names to thank including Ben's pal Matt Damon, a producer on the movie, but missed out the actor, who pretended to be unimpressed during an appearance on Jimmy Kimmel Live! on Monday (09Jan17).

"He thanked a s**t load of people, I got to tell you the truth," he said. "Someone was omitted… I was a little taken aback... That’s not the kind of thing I would do. If it’s me, you know, I thank people."

Jimmy showed footage of Ben and Matt accepting their joint Academy Award for writing Good Will Hunting in 1998 and Ben is listing actors from the movie to thank and it is Matt that reminds him "your brother" and Ben picks up on the cue and thanks Casey.

Defending himself, Ben said, “I needed a little push, but I did say, 'My brother, who's brilliant.' Those words came out of my mouth... We didn't hear anything like that last night."

To get revenge, Ben chose to humiliate his brother on the show. Following on from Jimmy stating they will make history if Casey, 41, wins an Academy Award, as it would be the first time brothers have won Oscars in separate categories, Ben continued by telling embarrassing stories about his sibling.

"This would be the first time someone would win an Oscar who didn't brush his teeth from ages 10 to 14, it would be the very first time that someone wins an Oscar who pulls his pants all the way down at the urinal.

"The first person to win who's scared of butterflies. Not only that, he would be the very first person to win who used to touch himself watching Vicki the robot from (80s sitcom) Small Wonder."

He concluded by revealing Casey once asked if Back to the Future was a true story.

Ben, 44, told a different story when he spoke to ETOnline on Monday, saying watching Casey get the award was "the most memorable experience in my life" because he's believed in his talent for so long.