By Cliff Renfrew - Breaking Celebrity News Reporter

Talk show legend David Letterman took Julia Roberts by surprise after he 'double flipped-off' his audience live on air during The Late Show, and Breaking Celebrity News has the video.

The Larry Crowne star - who is one of Letterman's favorite celebrities -gasped after she realized he had given the crowd the two-fingered salute.

It happened after Letterman explained to the Oscar winner how his biggest sadness in life was that his son did not have a brother or sister.

When the audience interrupted his conversation with a half-hearted 'Awwwww' he let them have the 'double bird' to show his disapproval.

Roberts, 43, has three kids with her husband Danny Moder, twins Hazel and Phinnaeus (both 6) plus a son Henry, 4.

Letterman, 64, has a son Harry, 8, with his wife Regina Lasko.

Several years ago Letterman infamously did an inverted single flip-off to a viewer who sent him a letter claiming he watched the show upside down so that blood could rush to his head.