This one has been a favorite of mine since I was at least 5 or 6 years old:
Table Manners - I
The Goops they lick their fingers,
And the Goops they lick their knives,
They spill their broth on the tablecloth -
Oh, they lead disgusting lives!
The Goops they talk while eating,
And loud and fast they chew,
And that is why I'm glad that I
Am not a Goop – are you?
By Gelett Burgess, published in Goops and How to Be Them: A Manual of Manners for Polite Children. This book was originally published in 1900 and I absolutely loved it as a child. At one point, I had every single poem memorized.
Not only are the poems great, but the illustrations are utterly charming as well: