Idiom - Wikipedia
https://en.wikipedia.org/wiki/IdiomMany idiomatic expressions were meant literally in their original use, but sometimes, the attribution of the literal meaning changed and the phrase itself grew away from its original roots—typically leading to a folk etymology. For instance, the phrase "spill the beans" (meaning to reveal a secret) is first attested in 1919, but has been claimed to originate from an ancient method of voting by depositing beans in jars, which could be spilled, prematurely revealing the results.