There was quite a bit of discussion for the first few days after their visit about the tooth fairy, the quarters she brings, the time she forgot to take Macey's tooth, etcetera, etcetera. Until finally Macey asked, "Mommy, if fairies aren't in real life, how is the Tooth Fairy real?"
My response: "What do YOU think?" :) They'll figure it out eventually, but I'm not going to rush it!