Actor-filmmaker Ben Affleck tipped a waitress over $90 when he bought a cup of coffee.

The generous `Argo` star was in a rush while in a coffee shop in Santa Monica, California, and left the waitress a huge tip when he realised he was only carrying $100 notes, reports contactmusic.com.

A source said: "The clerk told him it was so early that she didn't have enough change in the register and could he wait while she went to the back office safe. But Ben told her, 'Don't bother - you keep the change.'

"She balked at first, but when Ben insisted, she said, 'Wow, that is so nice of you! My mom's visiting form Winsconsin, and I'll take her out to dinner with this.'"

As he departed, Affleck told the waitress: "Good, tell her I said Hi."