Each week , we tell the story of words and expressions often used in American English . Some of them are old . Others are new . Together , they form a living language . On today's show , we will be talking about the act of hitting someone with the palm of your hand . We call this a slap ! Growing up , you may have experienced a slap or two . Do you remember how it felt ? Probably not good . And when the slap is on your face , the feeling is even worse ! You often do not see it coming until the open palm lands on your cheek . The sting on your face can cause tears to well up in your eyes . And you may feel insulted and offended . And that brings us to today's expression : a slap in the face . Used as an expression , “a slap in the face ” is not a physical act . It is a surprising action or comment that offends someone . A slap in the face is humiliating and can also cause disappointment . Word experts say the expression dates back to the late 1800s . It may have come from the idea of defending yourself against unwanted sexual attention . When that happens , you might slap that person across the face . Generally speaking , in the 1800s women would likely be the ones slapping men in those situations . But the expression “a slap in the face ” could also come from an old tradition between men – the duel . A duel is a contest with deadly weapons arranged between two people in order to settle a point of honor . In the past , a man could challenge another to a duel by slapping him across the face with an empty glove . To protect his honor , or to save face , the slapped person must agree to the duel . Today , the expression “a slap in the face ” means an insult . More often than not , “a slap on the face ” is done on purpose . It is intentional . Now , let's hear how to use “a slap in the face ” in everyday life . Imagine actors preparing for a big show . Catherine is in the studio rehearsing her song . Then suddenly , Oscar bursts into the room . He is so angry he can barely speak . Catherine stops singing and stops the music . Oscar , I'm right in the middle of my big song . What's the matter ? But I just got some really bad news . My name is Catherine . Can we please stop talking about you for a minute ? The director is giving my part in the show to Manuel ! She said that Manuel is really talented and deserves to play the lead . What a slap in the face ! Your face , I mean . I know how that idiom works , Catherine . So , what else did she say ? She said that lately I've been very ‘unprofessional .’ She must be talking about all those rehearsals you've missed . But the show opens in a week . What are you going to tell your friends and family ? I have no idea . They've planned a big opening night party and everything . This is so humiliating . How can I face them ? That's going to be a huge loss of face … again I'm talking about your face . Can you stop with the all these humiliation idioms ?? They're not helping ! But wow , what a blow . What a blow , indeed . The director's decision is certainly a major slap in the face . As we heard in the dialogue , you could also say that the news came as a blow to Oscar . In other words , the director's decision was surprising , unwanted and hurtful . It did damage as a blow would do . And Catherine really increased the tension with all of her idioms of humiliation . And that's all we have for you on today's show .