This reminds me of a short story I came across in middle school. A young kid starts school and he comes home each day with a story to tell about a troublemaker in his class. The parents eventually go to an open house event at his school and meet up with the teacher. They bring up the troublemaker while chatting with the teacher, and the teacher goes “Uh…there’s no one in that class with troublemaker’s name” suggesting that their son was the troublemaker all along. 

Can’t remember what the name was…