A Question for Thurl Ravenscroft

You say you’ve never heard of Thurl Ravenscroft? Oh, but you have:

Now, I have a question. Towards the end of the song are these lines:

The three words that best describe you
are as follows, and I quote:
“Stink!”
“Stank!”
“Stunk!”

Just who is being quoted here, though? Is it Seuss? I didn’t think the words appear in his story . . .

Any ideas?