My DD was 6 when she lost a tooth during Christmas season, which prompted a conversation with an older friend on the reality of the Tooth Fairy and Santa. So she came to us with the question, and actually used the phrase "tell me the truth"... because while we strive to be perfectly honest with our little one, we're not above a little mischievous trickery whenever the opportunity presents itself.
Interestingly, learning about the Tooth Fairy didn't seem to bother her too much. "Daddy is the Tooth Fairy" seemed to be a concept she liked. But she was pretty unhappy to learn about Santa. Then, a few days later, she declared, "I want to believe!" And so, she does.
