A slap in the face

A slap in the face is an idiom that may not be as old as you think. An idiom is a commonly used word, group of words, or phrase that has a figurative meaning that is not easily deduced from its literal definition. Often using descriptive imagery or metaphors, common idioms are words and phrases […]
from Grammarist
https://grammarist.com/idiom/a-slap-in-the-face/