On this show , we explore the origins and usage of common expressions in American English . During September in the United States — and in many places around the world — children are going back to school . Naturally , we all want to do well in school and life . Sometimes we do , sometimes we don't . So , today we are going to talk about both . The expressions you will hear in today's program are commonly used in a classroom . But , they can also be used in other situations . Let's start with the bad situations first . In American slang , when something bombs , it fails completely . So , if you fail a test , you bombed it . For example , if a comedian is on stage telling jokes but no one is laughing , you can say his jokes are bombing . Afterward , if you are feeling very mean , you could say to him , "Wow , you really bombed ." Now , let's say nobody goes to the new superhero movie , you can say it bombed at the box office . The box office is where people buy their movie tickets . In this case , they were buying tickets for a dud or a flop . These two words are often used to describe a form of entertainment that failed in its purpose -- to entertain . Even a party that bombs can be called a dud or a flop . And if a class you are taking is boring or useless , you could call it a "a real dud ." Now , let's go back to bombing . That means they are great -- in a cool , awesome kind of way . For example , let's say your boss wears a new suit to an important meeting . You look awesome !" So , as we said , be careful ! Now , let's talk about expressions to use when you do something really well . Let's say you did well on a test . You got 100 % correct . You aced it ! You can also say that you passed with flying colors . The last expression might make you think of a big celebration — like maybe your parents celebrated your passing grade by lighting colorful fireworks . But you would be wrong . Word experts seem to agree that the expression "to pass with flying colors " comes from the military . In this case , “pass ” doesn't mean to succeed , but to travel . And “colors ” doesn't mean shades like red or blue , but flags . According to the website The Phrase Finder , “pass with flying colors ” originally describes winning ships sailing into port “with flags flying from all the mastheads .” By around 1700 , the phrase was being used to describe any kind of victory . Let's say you are nervously waiting in a doctor's exam room for the results of a blood test . The doctor may come in and say , "Don't worry ! I'm looking at the results of your blood test and you passed with flying colors !" It's not as if you studied for your blood test and then did well on it . So , this is the doctor's way of being lighthearted or funny .