这个短语的字面解释是“打手腕”，这是什么意思呢？请看对话：

    A: I thought I’d get a slap on the wrist for speeding, but I got fined US$300.

    B: That’s a lot of money. Where were you caught speeding?

    A: On the Shenzhen-Guangzhou expressway.

    B: You must have been driving very fast indeed!

    Note: At least since the 18th century the word “slap” was used figuratively as well as literally. A certain action could be a “slap on the face” or a “slap in the eyes,” that is, an attack or slur, a censure or reproof, either spoken or written. Imagine a child reaching for the food before everyone is seated round the family table. That’s when the child’s mother or father may give him a slap on the wrist. So this idiom means literally “a hit on the wrist as a mild punishment” or generally “a light punishment for doing something wrong.”