there's a good boy/girl

1. Used to encourage or give praise to a child or animal, especially a pet. Go help your mother clean the dishes—there's a good boy. There's a good girl! Now, stay.

2. Used to give condescending, patronizing, or belittling praise to someone. Now, go tell your boss that I need his signature on this docket; there's a good girl. Fetch me a cup of coffee, will you? There's a good boy.

ˈthere’s a good boy, girl, dog, etc.

(informal) used to praise or encourage small children or animals: Finish your dinner, there’s a good lad. ♢ Sit! There’s a good dog.