What Do You Say Meaning

(idiomatic, childish) Used to remind a child to say a polite expression.

Example:   Let's go to the movies tonight, what do you say?
  That man just gave you a lovely birthday gift, young lady; what do you say? ― Thank you!
  I want cake! ― What do you say? ― Please!
  When Aunt Fiona from Florida gave Jordan some candy, Mom said, "What do you say?" Jordan replied, "Thank you!"