Four brisk lines of manners: come when you're called, do what you're bid, shut the door after you, and never sulk about it. Short enough to remember after a single read.
From Mother Goose / Nursery Rhymes (traditional). See the whole collection.
Come when you're called,
Do what you're bid,
Shut the door after you,
And never be chid.
Public domain. Text from The Real Mother Goose (Blanche Fisher Wright, 1916), via Project Gutenberg. View the source edition