Mechanical rice picker

From Memory Alpha, the free Star Trek reference.

A mechanical rice picker is an agricultural device used on Earth for picking rice, or so told James T. Kirk to a 20th century police officer in an attempt to explain Spock's ears.

In Kirk's improvisation, he told the police officer who caught Spock and him stealing clothes that the "obviously Chinese" Spock got his head stuck in such a device as a child. The local missionary had to use his plastic surgery skills to save Spock's life, with the unfortunate side effect of pointing his ears. (TOS: "The City on the Edge of Forever")