Don't tell secrets in corn fields. Too many ears around.
Why this joke works
Every Cornstalk Is Listening
Each cob of corn is called an ear, while ears are also what people use to overhear a secret. A corn field can therefore contain hundreds of “listeners” without any people nearby. Deliver the warning quietly, as though protecting genuinely private information. Pause after “corn fields,” then glance around before mentioning all the ears. The small performance helps the ordinary farm term shift into the body-part meaning without needing to explain why the field suddenly seems crowded.
A closer look
A Warning Creates the Suspense
Opening with “don’t” gives the line the urgency of practical advice. The listener briefly wonders what danger a cornfield poses before the second sentence reveals an audience rather than a hazard. “Around” expands the picture in every direction, as if the speaker has suddenly noticed countless eavesdroppers. A lowered voice can turn the field into a comic conspiracy.
Fact behind the joke
Corn Ears Have Even-Numbered Rows
USDA nutrition material notes that an ear of corn has an even number of kernel rows. The ear is a flowering structure attached to the stalk, not a hearing organ, but its name has been standard agricultural vocabulary for centuries. That familiar farm term lets the joke fill an empty field with imaginary listeners.