Hello! There are a few ways to use the word crunch. As far as what you have said the first and the third are common ways of using crunch in America. I have never heard it be said how you used it in the second sentence. Other ways to use crunch would be: The machine can crunch cars as if they were only pop cans. In this crunch is the action of smashing the cars. Example 2: Chips make a loud crunching sound when being ate. Crunch here is describing the sound of chewing the chips. Example 3. When at the gym working out yesterday I did a lot of crunches to help my abs. A crunch is an exercise like a sit up but you just have to get your shoulder blades off the ground you don't go all the way up. I hope you find this useful!