Ben Affleck has roasted younger brother Casey Affleck on Jimmy Kimmel Live after the actor forgot to thank his famous older sibling while collecting his first Golden Globe.
The lesser-known Affleck sibling won the best actor gong for film Manchester by the Sea on Monday and in his acceptance speech thanked everyone from Amazon CEO Jeff Bezos to Matt Damon for his "support and friendship".
With Kimmel as an accomplice, Ben got his own back by detailing Casey's childhood secrets on national television, including the fact he once thought Back to the Future was a real story.
"Your brother, he thanked Amazon, which is a company from which you order soap," Kimmel said incredulously.
"He thanked Matt Damon, who's a vile person in general," Affleck joked about his best friend. "He thanked a s---load of people, Jimmy."
"There was one person that I noticed was not mentioned," Kimmel continued. "His role model. The man who blazed the trail for him in showbusiness. His brother, Ben."
"I was a little taken aback. That's not the kind of thing I would do. I thank people," the actor said.
Kimmel then played footage of Ben's acceptance speech from the 1998 Oscars for Good Will Hunting and, sure enough, he thanks his younger brother Casey.
"My brother Casey, who's brilliant in the movie," a fresher-faced Affleck gushed at the time.
Anticipating Casey would also win best actor at the Oscars next month, Affleck described all the ways it would be historic.
"Would this be the first time brothers have won in separate categories?" Kimmel asked him.
"This would be the very time someone would win an Oscar who didn't brush his teeth from ages 10 to 14," the actor said.
"I didn't know that about Casey!"
"This would be the very first time someone wins an Oscar who pulls his pants all the way down at the urinal. Most Oscar winners don't do that," Affleck continued, sticking the knife in.
"This is special!"
"The first person to win who's scared of butterflies. He would be the first person to win who used to touch himself watching Vicki the Robot from [80s American sitcom] Small Wonder.
"Last but not least - I'm going to get one more in - this would be the very first person to win an Academy Award who once asked his brother if Back to the Future was a true story."
Fear of butterflies or not, considering Affleck's most recent film Batman v Superman was universally panned by critics, it looks like Casey might get the last laugh at the Academy Awards.