Magic

There was this magician who was playing some smart tricks on the road side. One boy went to him and the man said to the boy, "I will just touch your forehead and write your actual name on this paper. If I am wrong then I will give you some of my magic stuffs, otherwise you have to give me $50." The boy agreed as he thought that no matter what name he writes, he will deny it. At the end, the boy was the one who lost the bet. How?