The scheme entailed the sale of a "suckling pig" in a "poke" (bag). The wriggling bag actually contained a cat, not particularly prized as a source of meat, that was sold with the bag unopened, to the victim.

The French term acheter (un) chat en poche (to buy a cat in a bag) refers to the fact, as do many European equivalents, while the English expression refers to the appearance of the trick.

A common colloquial expression in the English language, to "buy a pig in a poke," is to make a risky purchase 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 languages, most of them meaning to buy a cat in a bag, with some exceptions.

This trick also appears to be the origin of the expressions "Let 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); and "left holding the bag," meaning 'to find oneself with nothing for their efforts,' as the cat (and perhaps the customer) is quite likely to flee when the bag is opened.

"Pig in a Poke" is a fictional game show in the 1985 comedy film National Lampoon's European Vacation (which was based on Family Feud, but had the families wear pig costumes).