“You have nice manners for a thief and a liar,” said the dragon. “You seem familiar with my name, but I don’t seem to remember smelling you before. Who are you and where do you come from, may I ask?”
“You may indeed! I come from under the hill, and under the hills and over the hills my paths led. And through the air. I am he that walks unseen.”
“So I can well believe,” said Smaug, “but that is hardly your usual name.”
“I am the clue-finder, the web-cutter, the stinging fly. I was chosen for the lucky number.”
“Lovely titles!” sneered the dragon. “But lucky numbers don’t always come off.”
“I am he that buries his friends alive and drowns them and draws them alive again from the water. I came from the end of a bag, but no bag went over me.”
“These don’t sound so creditable,” scoffed Smaug.
“I am the friend of 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).

Chapter 12 Inside Information