High tech tooth fairy

Rion has had a tooth loose for a few days and yesterday it finally fell out. Ok, Torii knocked it out, but the point is, the tooth came out. As we were talking about the tooth fairy Torii asked me how she knows when there is a tooth under your pillow. "I don't know" and "she just knows" were not satisfactory answers for him. Finally I told him, "When your tooth falls out, the tooth fairy gets an email so she knows to visit you that night." He didn't ask anymore questions.