Justin Timberlake celebrated TBT in the truest, boy-bandiest way possible last night when Joey Fatone surprised him onstage at his New York City show Thursday.

His NSYNC buddy had been partying up in the Hammerstein Ballroom balcony during the show until he disappeared, reappearing onstage during "Suit & Tie." While Joey was singing with the Tennessee Kids, Justin was unaware, despite screams from the audience.

And after a few moments of oblivion, JT turned around, saw his ol' NSYNC pal and said, "Let's hear it for the Fat One!" Don't act like you've never called Joey that (love you, Joey).

All in all, the surprise bumped up the fun during the high-energy concert.

While Joey served as one #TBT, Justin reminisced with another throwback when he posted an old-school picture of him as a toddler. Holding a baby banjo, a confounded JT joins a grown-up band, complete with stand-up bass, guitar and big-boy banjo. Guess he's been a musician all along!