It’s official: my two favorite fictional worlds are colliding! Upper East Side meets L.A. West Side as Blair Waldorf ditches class at Constance Billard to hang (or perhaps even canoodle?) with leading man Vincent Chase. Okay, so it’s not the Queen B herself but alter-ego, actress Leighton Meester (pictured), who will guest star on Entourage, but I’m pretty excited nonetheless. HBO has confirmed to EW.com that the Gossip Girl star will reprise her Entourage season 1 role as Britney Spears-esque pop tart Justine Chapin on an episode of the comedy. Meester has a knack for playing the virginal sexpot, so we can only guess what sparks will fly when she heads back to the left coast.