"I am the friend of the bears and the guest of eagles. I am Ringwinner and Luckwearer; and I am Barrel-rider," went on Bilbo beginning to be pleased with his riddling. "That's better," said Smaug. "But don't let your imagination run away with you!" This of course is the way to talk to dragons, if you don't want to reveal your proper name (which is wise), and don't want to infuriate them by a flat refusal (which is also very wise).