" A pig in a poke "
Meaning:
A commodity that is bought without first examining it.
Example:
Jim said that car was a good buy so I bid for it on eBay and it turned out to be a real rust bucket. That’s what you get for buying a pig in a poke.
Where did it originate?:
The United Kingdom. An old expression that exists in various forms in many languages.
Where is it used?:
Hear the idiom spoken: