The key to understanding your dream is in your emotions about the dream. You seem rather "insulted" that you would smoke weed, and even dream about smoking it. It is beneath you, and beneath your dignity to do drugs, so why did you dream about it? In some way, your character was in question in real Life, and you were insulted by this. In dreamland, you equate this incident to smoking pot. Look back on the last several days and see what incident occurred which through your character into question and made you ill at ease. And your reaction was of shock because you don't even do petty crimes!!