Close....But Still Not Quite Right

As I set Matthew's dinner plate in front of him....
Matthew says "Thank you, sir." (Matthew calls me sir ALL the time, but I don't often correct him because is so young and he is still being polite)
Erik: "Mama is a girl, so you say thank you, ma'am."
Matthew: "Oh ok, Daddy."
I deliever a cup to the table.
Matthew shoots a quick glance toward Erik and then looks at me and says with pride and confidence: "Thank you, man."