We also give you examples of how we use these expressions in everyday conversation . Today we explore expressions using the word “bullet .” And it comes out fast . In fact , that used to be the way to describe the speed of the superhero Superman -- he is “faster than a speeding bullet .” And that is why very fast trains are often called "bullet trains ." Bullets are not only known for their speed . However , not all bullets are bad . A magic bullet -- sometimes called a silver bullet -- is something that solves a difficult problem easily . We often use these two expressions in the negative , because usually there is not one thing that solves a difficult problem . For example , let's say a country is suffering from a weak economy . People lose their jobs . Some families lose their homes . This leads to an increase in mental and physical health issues . After many years of such conditions , people want change . So , they protest in the streets . Yet , there is no silver bullet to cure all these problems . To take a bullet for someone is a good thing . Well , the thought behind this expression is a good thing . It means you are willing to put yourself in harm's way to protect someone else . This often sounds like a tough expression . Mothers might not say I'd take a bullet for their child , but they would . People in the military , however , might say , “I'd take a bullet for you , man .” Now , we know that sweating is our body's way of keeping cool . But we also sweat when we're nervous . When you sweat bullets you are very nervous or anxious about something . If you dodge a bullet , you have successfully avoided a problem -- but barely . For example , let's say you get up late for work . Your boss has already warned you that if you come in late again , you may get fired . When you arrive at the office , you are sweating bullets -- you are nervous and very worried that your boss will fire you . However , you need not worry . As it turns out , your boss is out sick that day . You have dodged a bullet . To ease the pain of a difficult situation , people are sometimes asked to bite the bullet . This actually sounds like really bad advice . What is the origin of this expression ? The story may go back to the American Civil War or even earlier . War is painful . And our bodies have many natural responses to pain . We tighten our fists , tense our muscles or clench our teeth . So , doctors working on the battlefield would give their patients a piece of wood to squeeze or something soft to bite on . Many times the nearest thing was a soft , lead bullet . Hollywood movies helped to keep this expression alive . But that is in the movies . In modern conversation , “biting the bullet ” means to accept a difficult decision or situation . It hints that a person has been putting off this difficult decision . If you want to perfect your English , there is no silver bullet . You must simply practice and study as much as you can .