I'm going to disobey my stepfather
What is your purpose for wanting to disobey your step father?
Because I'm smart to do so.
Even if you think that you are smart enough to get away with it, it is not good to disobey your stepfather. It will upset him and your mother and could get you grounded.
I'm not listening to you.
There is no reason to disobey your stepfather, especially if you are just doing it to do it. Really try to hear him out as he is in charge of taking care of you.