Taylor Swift, Carly Simon duet on 'You're So Vain' Carly Simon, left, joined Taylor Swift at Gillette Stadium in Foxborough, Mass., to sing Simon's hit "You're So Vain." Theo Wargo / TAS / July 27, 2013 By Randy Lewis August 1, 2013, 1:25 p.m. Taylor Swift has built a career dropping hints to the identities of bad boyfriends in hit songs as an example of the adage for the broken-hearted, "Don't get mad - get even." Last weekend when Swift's "Red" tour reached Foxborough, Mass., she brought out Carly Simon, the woman who has kept listeners guessing for more than 40 years about the subject of her kiss-off song "You're So Vain." "When I heard "You're So Vain," I thought, that is the best song ever," Swift said. That is the most direct way anyone has ever addressed a breakup.... Every girl out there will be thinking of someone when we're singing. PHOTOS: Taylor Swift at the Staples Center The two sang it together Saturday in front of some 55,000 fans at Gillette Stadium, one of two sold-out shows at the venue as part of Swift's tour that reaches Southern California for shows at Staples Center on Aug. 19, 20, 23 and 24. Here's the video with excerpts from the "You're So Vain" performance and interview footage of Swift and Simon, before and after their duet: Taylor Swift makes a grown-up move on 'Red' Carly Simon: Coming around again with 'This Kind of Love' The Forum aims to rock rival Staples with major renovation Twitter: @RandyLewis2