Fare orecchie da mercante

Literally: To make merchant's ears

Example: “Quando parliamo di pulizie, fa orecchie da mercante.” — When we talk about cleaning, he turns a deaf ear.

English equivalent: To turn a deaf ear

Origin: Merchant's ears are ears that hear only what suits them. The phrase is in written Italian from the 14th century, and Manzoni uses it in I promessi sposi. The traditional explanation is the market trader who pretends not to hear complaints or requests that would cost him money, but no source documents it.