Goops and How to Be Them by Frank Gelett Burgess (1886 - 1951)

From the publisher

Let me introduce a Race Void of Beauty and of Grace, Extraordinary Creatures With a Paucity of Features. Though their Forms are fashioned ill, They have Manners stranger still; For in Rudeness they're Precocious, They're Atrocious, they're Ferocious! Yet you'll learn, if you are Bright, Politeness from the Impolite. When you've finished with the Book, At your Conduct take a Look; Ask yourself, upon the Spot, Are you Goop, or are you Not? For, although it's Fun to See them It is Terrible to Be them! - Summary by Gelett Burgess