Same fate for "stubborn as a mule." Who among us these days knows the depth of a mule's character? Without an understanding of mules, this comparison doesn't help us get a clear picture of anything.
Back in the day, however, people who knew mules hearing this would nod sagely and think, "That was one stubborn fella."
Sometimes a phrase wanders so far its origin as to be nonsensical: "avoid it like the plague," "dead as a doornail," or "three sheets to the wind"? Wha--? A person can parse them to make sense, but the expressions are fossils.
With that in mind, today's visual pun came as a fresh view (to me at least, after Uncle Mark pointed it out) of a fairly common phrase. Be the first to identify the phrase in a comment below and win a prize.