So what is a “pig in a poke”?
It´s an expression which means that you´ve bought something of less value than you thought because you didn´t check it out properly.
Its origins are from market sales in the middle ages where pigs were bought and sold, and if you´d bought one in a sack (a poke) without checking it out you might find that you´d been “sold a pup”.
This confidence trick also led to the term “letting the cat out of the bag”. When you opened your sack you found a cat (or puppy – hence you´d been “sold a pup”).
The expression “pig in a poke” now applies to anything that you´ve bought which is found to be next to useless! As does “being sold a pup”, whereas “letting the cat out of the bag” means giving up a secret usually inadvertently.
Discover your pig in a poke and other porcine expressions, courtesy of Oxford Dictionaries using this link!