My son is 7 and has lost 3 teeth in the last 12 months. Last time the tooth fairy (me writing very small) left him a note and he was so thrilled and excited and believed me that she was real. He wanted a note from her last week but I forgot didn't get one as he had been naughty. He mentioned it later too. We were meant to be going to buy him a toy he had saved for tonight but I have said no as they all were naughty this morning. I hit on the idea of the tooth fairy leaving a note saying she was disappointed he was naughty as she had been looking forward to seeing him with his new game. I just thought it might be a fun way to get a point across but am I going to make him mistrust me in future or cause any other problems?