Justin Timberlake got the party started at Trousdale lounge in Los Angeles. The singer-actor and his pals took over part of the back room, where they ordered bottles of champagne. “He was in great spirits,” a source tells PEOPLE. “He was nice and friendly with everyone he talked to, laughing and making jokes to his guy friends.” Though he talked to a few lucky ladies, he was focused on having fun with his friends. Later, Gossip Girl‘s Chace Crawford, there with his own group, stopped by to say hello.