Justin Timberlake had the ultimate Throwback Thursday moment when 'N Sync's Joey Fatone surprised him onstage at his New York concert last night. Joey spent most of the evening partying on the Hammerstein Ballroom balcony, dancing along to Justin's hits. However, when Justin started singing "Suit & Tie," Joey appeared onstage and began singing backup. Despite screams from the crowd (who knew, Joey has fans), Justin seemed oblivious until he turned around and laid eyes on his bandmate. He then announced, "Let's hear it for the Fat One!" (C'mon -- surely you've called him that, too.)