Garfield by Jim Davis for September 06, 1983
Transcript:
Garfield: Silly me had to fall into the heating vent. Now here I am, residing deep within the bowels of my home. Forced to spend my remaining days fending for myself in the tin tunnels of the duct work, the solenoid jungle of the wiring system and the polyvinyl chloride playground in the crawl space. Hey! I think there's a book here somewhere.
I think the joke is that his vocabulary got more refined because he was in proximity of a book. That’s the best guess I have.