An old chestnut is a story that has been repeated many times and has become dull. This phrase first came into existence when in the well-liked 1816 melodrama play Broken Sword two characters exchanged these lines:
Zavior. Let me see–ay! it is exactly six years since that peace being restored to Spain, and my ship paid off, my kind brother offered me a snug hammock in the dwelling of my forefathers. I mounted a mule at Barcelona and trotted away for my native mountains. At the dawn of the fourth day’s journey, I entered the wood of Collares, when, suddenly, from the thick boughs of a cork-tree–
Pablo. [Jumping up.] A chesnut, Captain, a chesnut!
Zavior. Bah, you booby! I say, a cork!
Pablo. And I swear, a chesnut. Captain, this is the twenty-seventh time 1 have heard you relate this story, and you invariably said, a chesnut, till now.
After this, newspapers began referring to stale stories as chestnuts. Old was later added for emphasis. And eventually the phrase old chestnut made it’s way into common vernacular.