In moving-slow he has no Peer.
You ask him something in his Ear,
He thinks about it for a Year;

And, then, before he says a Word
There, upside down (unlike a Bird),
He will assume that you have Heard-

A most Ex-as-per-at-ing Lug.
But should you call his manner Smug,
He'll sigh and give his Branch a Hug;

Then off again to Sleep he goes,
Still swaying gently by his Toes,
And you just know he knows he knows.

Theodore Roethke

http://www.poemhunter.com/poem/the-sloth/