(Informal) Be extremely expensive. Cost a lot of money.
Mary’s dress is pure silk. It must have cost an arm and a leg.
It cost an arm and leg, so I didn’t buy it.
Notice how interesting is the way idioms work in English and give this fluency to the situation. Similarly, we in Brazil have a lot of idioms and for the one here, we also use part of the body to describe something as expensive: “custar os olhos da cara”!
It´s really amazing how languages work. Did you like this one? Share the post and put your suggestions on the comments. And thanks for visiting:P