a pig in a poke

US /ə pɪɡ ɪn ə poʊk/
UK /ə pɪɡ ɪn ə poʊk/
"a pig in a poke" picture
1.

袋の中の豚, 中身の見えないもの

something that is bought or accepted without first being seen or examined

:
Buying a used car without a test drive is like buying a pig in a poke.
試乗せずに中古車を買うのは、袋の中の豚を買うようなものだ。
I'm not going to sign this contract without reading it first; I don't want to buy a pig in a poke.
まず読まずにこの契約書に署名するつもりはない。袋の中の豚を買いたくないからだ。