I used to play piano by ear.

The phrase "playing by ear" is a familiar one in the world of music, describing a musician who can reproduce melodies and harmonies just by listening, without relying on sheet music. It's a skill that speaks to a natural talent for pitch and musical memory, often admired in improvisational genres like jazz or folk. Many a virtuoso has started their journey by simply listening and mimicking, developing a deep intuition for sound.

This joke cleverly twists that well-understood idiom into a literal and utterly absurd image. The setup leads us to expect a story about musical development, perhaps learning to read music or mastering a new technique. Instead, the punchline yanks us into a bizarre scenario where someone might physically use their ear to press piano keys, before revealing the obvious and logical method of playing – with hands. The humor springs from this unexpected literal interpretation, creating a silly mental picture that clashes with common sense, and relies entirely on our brain's automatic processing of idioms versus their literal meaning. It's a classic example of wordplay turning a common phrase on its head for a quick laugh.