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.

A source told National Enquirer magazine: ''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, Ben told the stunned waitress: ''Good, tell her I said Hi!''

Ben is not the only generous star in Hollywood. Rihanna has been known to tip a waiter $200 while George Clooney paid for a nearby table's dinner at a Berlin restaurant simply because he thought he and his friends were being too loud.

However, one of the most generous of all is Ellen Degeneres, who upon hearing New Hampshire waitress Sarah Hoidahl had picked up the a $30 bill for two National Guard soldiers affected by the U.S. government's shutdown, presented her with a cheque for $10,000.