It may not be the most popular or favorite thing to do, but having the ability to impress adults can be an extremely helpful skill, in school and in the workplace.
First, you want to dress nicely. Adults like to see a clean cut well-dressed young man/young lady. Don't try anything daring or something you think might be scandalous. It will only make them think less of you. Remember, they probably still think of you as children, so cleavage or visible boxers are probably not a good idea, nor are they appropriate.