George Clooney Sings 'Sweet Caroline' With Neil Diamond at Carousel of Hope Ball (Video)

George Clooney: actor, director, humanitarian -- and singer?

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At Saturday's Carousel of Hope Ball, where Clooney was the honoree, he joined up with Neil Diamond for a duet of the singer's classic "Sweet Caroline."

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As Diamond sang the lyrics "good times never seemed so good," Clooney jumped in with the "so good, so good" response that fans have added over the years. The actor appeared to be having a good time while giving a mock-serious delivery of the lyrics.

Barbara Davis, the chairperson of the Carousel of Hope Ball, praised Clooney's impromptu performance.

"When he was growing up, he thought he'd be a singer because his aunt (Rosemary Clooney) was such a big singer," she told The Hollywood Reporter. "But when he went into the studio, people just stared at him. … It's clear he's a better actor and director than a singer. And on this night he was also a good sport."

Many in attendance cheered on Clooney and recorded the once-in-a-lifetime event on their cameras and cellphones, posting the videos on YouTube. (Watch one below.)

At the event, Clooney was presented with the Brass Ring award for his humanitarian efforts around the world. Presenter Shirley MacLaine called him the “most generous, sweetest, charming human being I know.”

STORY: George Clooney Honored at Carousel of Hope Ball

In his acceptance, Clooney spoke of his work in Darfur and said, “You can’t make people do the right things, but you can make it harder for them to do the wrong things.”

Proceeds from the Carousel of Hope Ball go to the Barbara Davis Center for Childhood Diabetes in Aurora, Colo., for diabetes treatment and research. Saturday's dinner raised more than $2.5 million.