I said to a student this morning, in a voice of authority, and immediately thought of a statue of some towering figure who ruled with an iron fist and sharp tongue --- the least of his (or her) weapons against humanity.
I won't tell you again means I just told you How many times to do I have to tell you You're not listening you are stubborn and insolent, I am wronged. What you have done is egregious, but what is worse is that you can't spell egregious or pronounce it or appreciate its meaning in a sentence.
What are you doing here, anyway, confounding me, interrupting my plan for how things are going to be? When I say quiet, I mean quiet, shut the door, sit down, pay attention. Pay attention. Pay attention to me. Build a mental statue in my honor, kneel there. How can you learn if you are talking instead of hearing me the first time I said I won't tell you again.
Outside the traffic hums. You will get in your car later and drive home to where, hopefully, there are a few kids just waiting to get on your nerves so that you eventually scream I won't tell you again!
In the dark you may cry because of someone's insensitivity, someone's impatience toward you, because you are in trouble but you won't tell anyone and you sure as hell won't tell me because I won't tell you again.