This is by Sailor Jim Johnston on alt.callahans.

Sailor Jim sticks his head in for a moment and asks, “Has anybody here ever heard the potato clock joke? No? Wanna hear the infamous potato clock joke?”

Hearing no objections, he takes a few deep breaths to steel himself and announces:

“Every morning, I get a potato clock!”

He quickly ducks back outside, while the masses are still puzzled. Wisdom often assumes the mantle of cowardly acts.