Moviemaker Rob Reiner has credited his When Harry Met Sally star Billy Crystal for the film's famous dinner table orgasm line that turned his mum into a star. Reiner was paying tribute to funnyman Crystal as he was awarded the 10th annual Mark Twain Prize for American Humor at the Kennedy Center in Washington, D.C. on Thursday night (11Oct07) when he revealed the `I'll have what she's having' line after Meg Ryan's sex prank was all the actor's idea. He told the audience, "Billy Crystal wrote that line." The director asked his mother Estelle, an extra in the diner scene, to deliver the line that has since become one of the great film utterances. Upon receiving the Mark Twain Prize, Crystal joked, "Does this mean I have to retire now?"