Hi Chloe. Amila has a good answer. Also, "knock'em dead" can be understood to mean several things. For example: "Knock'em dead" can mean that we are going to make a powerful impressions upon someone. For example, a couple of men might say this to indicate that they are going to make a wonderful impression upon some girls at a dance or a date or something similar. People could say that if they are about to give a sales presentation. Amila and I could say this to each other about the effect we have when we answer questions about English on italki. A Political campaign manager might use the expression about his Candidates upcoming speech or a tour through a certain region of the country. "Knock'em dead would be what several girls say to each other when they are about to go on stage to perform their song or dance routine. In almost any human endeavor, we might use the expression to indicate that we will overpower or overcome any obstacle which stands in our way.

we will be much, much, much better than them :)