During a sold-out "Red" tour performance at Gillette Stadium in Foxborough, Mass., Taylor Swift turned the show into a giant karaoke party when she invited Carly Simon on stage for a duet of her 1972 hit, "You're So Vain."
"Before I bring out my special guest, I have this question that I have always, always had," Swift teased as she introduced Simon. "I think you have probably had this question too, and wondered what the answer is: Who is the song 'You're So Vain' by Carly Simon written about?"
"As if!" Swift then sassed as the 68-year-old singer joined the pop country princess on stage for a breakup song sing-along.
Swift, who admitted backstage that she does know who the song was penned about but will never tell, said she is a huge fan of Simon.
"When I heard 'You're So Vain,' I just thought, 'That's the best song that's ever been written,'" she shared. "That is the most direct way anyone has ever addressed a breakup. It's amazing."
Simon also weighed in, saying that the song really helped shape her career in unexpected ways.
"It's a song that really sort of developed that style of mine," she said. "And a lot of it was not knowing that I was developing that style, because a lot of thing happen by accident, don't you feel?"
"Yeah, especially with songwriting," Swift responded.
After the performance, both stars tweeted love to each other.
"Got to sing 'You're So Vain' with Carly Simon at Gillette Stadium tonight!!!!! Unreal. I could not possibly look up to her more," Swift wrote.
"No!! I got to sing "You're So Vain" with Taylor Swift last night and I haven't had so much fun in many moons!!!" Simon tweeted back.
Check out the performance below. Who do you think "You're So Vain" is about? Leave your answer in the comments.
