This quaint little idiom, “a pig in a poke” quite literally means “let the buyer beware.” When someone buys or gets a pig in a poke it means they have purchased something sight unseen or without examining it closely. Example:
“I hope the used car I just bought doesn’t turn out to be a pig in a poke.”
Where did this phrase come from?
This is actually quite literal. It’s first recorded use originated in London in the early 1500s. John Heywood’s Proverbs, 1546, is quoted:
“Though he love not to buy the pig in the poke”.
The term “poke” means a small sack and can be traced back to the French word “poque”. Its diminutive is created by adding “ette” or “et” which is where we get the word “pocket.” A poke was the perfect size in which to stuff a piglet to carry it to market. An unscrupulous merchant was known to substitute a less useful and valuable for the piglet as it wouldn’t be discovered until the buyer had returned home. This was also the birthplace of the idiom “letting the cat out of the bag.”