Don’t take them literally.
1. Apple of my eye. The earliest recorded use of this comes from an Old English work attributed to King Alfred of Wessex (AD 849–899), who was referring to the apple-shaped pupil. Describing someone as the apple of your eye meant that he or she was as precious as eyesight. More modern references of this phrase turn up in the King James version of the Bible and Shakespeare.
2. Sell like hotcakes. If this phrase were invented today, it might be sell like funnel cakes or sell like deep-fried Twinkies. It refers to the big movers of county fairs past, when anyone with a hot griddle and some batter was certain to walk away with money bulging out of his pockets. Later in the 1800s the expression became a reference for any commercial success.
3. The big cheese. It’s got nothing to do with a dairy product. According to Sir Henry Yule’s 1886 Hobson-Jobson: The Anglo-Indian Dictionary, the expression derives from the Persian or Hindi word chiz, meaning quite simply a thing. Yule explains that Anglo-Indians might say something like “Lauren’s sister is the real chiz.” Brits living in India adopted the term, converting chiz into something more English. The idiom hit American shores in the 20th century. Americans seem to have a habit of putting big before nouns to convey wealth and power—the big enchilada, the big kahuna, the Big Apple. The first recorded examples of the big cheese being used to describe a person of important status began appearing in print around 1910.
4. Bun in the oven. It means there’s a baby on the way. The word oven has been a slang term for the womb since the 17th century, most likely with roots in Greek mythology. In her essay “The Oven in Popular Metaphor from Hosea to the Present Day,” Beryl Rowland suggests that the expression is a “colloquial use of an ancient folk metaphor.” Ancient gods were seen as millers and mills. Using this logic, Zeus and Hera were doing a lot of baking. The earliest published reference of this phrase is from the 1951 novel The Cruel Sea.
5. The best thing since sliced bread. Sliced bread is a relatively new invention, revealing its wonderment to the world in 1928. In the 1930s, Wonder Bread ads touting the innovation secured the phrase a place in idiomatic history. Suddenly, sliced bread was the measure against which all inventions were to be held.
6. Bring home the bacon. Perhaps it’s simply that the pig’s a valuable commodity. Or perhaps it refers to the baron in the English town of Dunmow in the early 1300s who offered a free side of bacon to any married couple who could swear by God that they had not fought in a year and a day. Another theory is that it refers to the popular county fair game that involved chasing and catching a greased pig. The prize? The pig, of course. The phrase grew in popularity after prizefighter Joe Gans, who had won the lightweight championship in 1902, telegrammed his mother that he was bringing home the bacon. Sports writers immediately picked it up.
7. Sing for your supper. In medieval times it was common for minstrels to sing songs and recite poetry in exchange for a meal at the local tavern. The saying evolved to mean doing any kind of service in exchange for something desired. It was popularized in the 1829 nursery rhyme “Little Tommy Tucker”:
Little Tommy Tucker sings for his supper,
What shall we give him? Brown bread and butter.
How shall he cut it without a knife?
How shall he marry without a wife?
8. Feel your oats. Horse owners in the 19th century noticed that their steeds had extra pep in their trot after receiving a meal of oats. It wasn’t long before this idea was applied to people as well.
9. From soup to nuts. This means everything, from start to finish; it originally referred only to meals. In the olden days, meals were long, elaborate events, very often starting with soup and ending with nuts. The phrase altered over the ages depending on the style of meal, giving us from eggs to apples and from pottage to cheese, but the meaning remained the same.
10. Take with a grain of salt. Some etymologists trace this phrase back to Pliny the Elder (AD 23–79), who found an antidote to various poisons that called for a pinch of salt—so poison taken with a grain (or pinch) of salt wasn’t so serious. But the phrase has been in use in English only since the 17th century, and makes more sense in the context of the dinner table: Food eaten with salt just goes down easier.