Pig in a poke

The idioms pig in a poke and sell a pup (or buy a pup) refer to a confidence trick originating in the Late Middle Ages, when meat was scarce, but cats and dogs were not. The idiom pig in a poke can also simply refer to someone buying a low-quality pig in a bag because he or she did not carefully check what was in the bag.

A poke is a sack or bag. It has a French origin as "poque" and, like several other French words, its diminutive is formed by adding "ette" or "et"—hence "pocket" began life with the meaning "small bag". Poke is still in use in several English-speaking places, including Scotland and some regions of the USA. For example among English hop growers, a poke is a large sack into which hops are poured to be taken from the picking machine to the oast for drying.

The scheme entailed the sale of a suckling pig in a poke. The bag, sold unopened, would actually contain a cat or dog, which was substantially less valuable as a source of meat. The French idiom acheter (un) chat en poche (to buy a cat in a bag) refers to an actual sale of this nature, as do many European equivalents, while the English expression refers to the appearance of the trick.

The English colloquialisms such as turn out to be a pig in a poke or buy a pig in a poke mean that something is sold or bought without the buyer knowing its true nature or value, especially when buying without inspecting the item beforehand. The phrase can also be applied to accepting an idea or plan without a full understanding of its basis. Similar expressions exist in other European languages, most of them referring to the purchase of a cat in a bag. To "let the cat out of the bag" may be a related idiom.

This trick may be the origin of the expression "letting the cat out of the bag", meaning to reveal that which is secret (if the would-be buyer opened the bag, the trick would be revealed).

In the April 1929 edition of the literary magazine London Aphrodite, a story by Rhys Davies, titled "A Pig in a Poke", was published, in which a Welsh collier takes a woman from London for his wife and regrets it. (Boulton 1993: p. 278)

The title of Georges Feydeau's 1888 play Chat en poche is taken from the French expression.

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