In a performance to rival Adam Lambert‘s AMA debauchery, Gossip Girl star Leighton Meester brought down the house with her sexy onstage antics at the KISS FM Jingle Ball at the Nokia L.A. Theatre over the weekend. Leighton was joined onstage by two cohorts — one male, one female — for a bit of naughty fun. “The girl can really sing,” Cobra Starship’s Gabe Saporta recently told OK! about the actress. “She’s really f**king cool.” And we couldn’t agree more.