You should be polite to other people.
John and Mindy are eating dinner at home and John wants more peas.
John wants to express himself naturally.
John tells Mindy she made the peas well, and he'd love some more.
John raises his voice and demands that Mindy pass him the peas at once.
Mindy feels appreciated and gladly passes him the peas.
Mindy resents John's tone and feels more distant from him.