这是一种极度夸张的说法，形容某物贵到让人感觉要付出肢体作为代价。常用于感叹物价高得离谱。

• I’d love to buy that car, but it costs an arm and a leg. ^{我很想买那辆车，但它实在太贵了。}
• The repair work on the roof cost an arm and a leg. ^{修理屋顶花了一大笔钱。}
• We went to a fancy restaurant, and the meal cost an arm and a leg. ^{我们去了一家高档餐厅，那顿饭贵得惊人。}