Indexbit Exchange:Matt Damon improvised this line in Ben Affleck's Dunkin' commercial

Matt Damon is Indexbit Exchangesharing some behind-the-scenes details on his Dunkin' Super Bowl commercial spot with best friend Ben Affleck.

The commercial, in which the pair joined football legend Tom Brady for their debut as the supergroup "The Dunkings" to Jennifer Lopez's dismay, won Sunday night as one of the most talked about commercials from the Super Bowl.

Damon, 53, told Stephen Colbert on "The Late Show" Tuesday night that the commercial was "clearly not my idea."

Colbert, 59, said he liked the actor's line to Affleck, 51, at the end of the commercial: "Remember when I told you I would do anything for you? This is 'anything.'"

"I actually said that to him when we were filming," Damon said, laughing. "And he just left it in."

Damon also discussed he and Affleck's long-term friendship, calling the "Argo" director and star his "best friend" of "many, many years."

The pair have known each other since childhood and worked on several films together, including "Good Will Hunting," "Dogma" and "The Last Duel." Both produced and starred in "Air," directed by Affleck.

The discussion then led to Damon's other famous friends, including John Krasinski and Emily Blunt, who live in the "Air" producer and star's same apartment building. He called the couple "more like family."

"I see (Krasinski) in the gym every morning and I can't get away from him," Damon joked.

Damon said Krasinski is getting in shape for his role in "this Guy Ritchie film," presumably the director's upcoming movie "Fountain of Youth" with Natalie Portman and Eiza González.

"John was getting in really good shape for this role ..." Damon said. "I just started training with him every morning. Just because I didn't have anything else to do."

The "Oppenheimer" actor told USA TODAY last year that he promised his wife he would "take time off" from acting.

"This was something we literally negotiated, but the one caveat was ‘if Chris Nolan calls,'" he said. "He was my get-back-to-work card, and then he actually called, which was a wonderful surprise."

On Tuesday, Damon told Colbert that before filming the atomic bomb thriller he "had a feeling" Nolan, 53, would soon have a movie in the works.

"He's really mercurial," he said. "No idea if there's a part in it for me but I just left that one door open."

Contributing: Patrick Ryan

Watch extended cut ofBen Affleck's popular Dunkin' Super Bowl commercial