Where does he work?

Where does he work?

A grade school teacher was asking students what their parents did for a living. "Tim, you be first. What does your mother do all day?" 

Tim stood up and proudly said, "She's a doctor." 

"That's wonderful. How about you, Amy?" 

Amy shyly stood up, scuffed her feet and said, "My father is a mailman." 

"Thank you, Amy" said the teacher. "What does your parent do, Billy?" 

Billy proudly stood up and announced, 

"Nothing. He's an economist."