Schwimmer will feature in the second season of Kudrow's Showtime series Web Therapy, and agreed to play the role after an invitation from Kudrow herself.
"I was really excited when [Lisa] called," Schwimmer told Access Hollywood.
"Actually, she e-mailed first and said, 'Hey, would you ever do a thing on the thing?' And I was like, 'Yeah!'
"Then I met with them, and we all talked about what the idea was and the character, and I have to say it was some of the most fun I've ever had."
Schwimmer will appear in four episodes of the show, playing a college professor's son who is traumatised after witnessing a "romantic encounter" between his dad and Kudrow's character Fiona.
"We got to play two completely different characters and improv for about six hours," Schwimmer enthused. "We just riffed and it was a blast."
The second season of Web Therapy premieres on July 2 on Showtime. Watch a trailer for the first season below: