Know Your Onions

Mike in Ukiah, California, grew up in the UK, where he often heard the expression to know your onions, meaning “to be knowledgeable about something.” He suspects the phrase is rhyming slang, but It’s most likely one of many metaphorical expressions based on being knowledgeable about products in a marketplace. The earliest seems to be from the 1840s, where to know one’s bean s or to know beans about something was used the same way. But there are also the phrases know your apples, know your sweet potatoes, know your vegetables, know your oats, know your bananas, know your fruit, know your eggs, know your cucumbers, know your goods, know your groceries, and know your oil, all of which mean the same thing. There might also be some transference from a French expression, s’occuper de ses oignons, which literally translates as “take care of your onions,” which means “mind your own business.” This is part of a complete episode.