It's a '90s fangirl's dream come true! On Saturday morning, Britney Spears gave us a fun dose of nostalgia when she uploaded a backstage photo of herself hanging out with Backstreet Boys' A.J. McLean on Instagram. Along with the snap, Britney made a shocking revelation, writing, "Huge confession... biggest @backstreetboys fan! Tonight was truly a dream for me. #Vegas #PieceOfMe." In case you may have forgotten, Britney was once an *NSYNC fan and even dated Justin Timberlake for what felt like an eternity. See Britney's post above now, and then watch her flaunt abs, lingerie, and massive tattoos in her latest video.