Producers at Kimmel approached Damon this past October to appear on the show for the host's 40th birthday celebration but he opted to keep the joke running.
As for creating the video, "I don't even think he thought twice about it," his rep tells PEOPLE. "He just said, 'I'll do it.'"
Damon shot the video with Silverman at the end of October in Miami. "He had so much fun," his rep adds. "It was his turn to get Jimmy."
Matt of many talents
We knew Sarah Silverman was funny, but who knew Matt Damon could go toe to toe with the comedian? A new music video on YouTube is so hilarious we almost spat out our morning coffee. In it, Silverman breaks the news to S.O. Jimmy Kimmel that she and Damon are - er, having a physical relationship. And who shows up to help make the point? Why it's Damon himself, who mugs, dances, and gamely gets jiggy. Silverman presented the highly bleeped bit during Kimmel's show Thursday night. It's all just a gag of course. The New Hampshire-bred Silverman and Kimmel have been an item for years. And Damon, well, the Cambridge actor has a future in stand-up if he tires of acting.