Do the "morgan" move! You may not win but at least your groin and honor will be intact.
Honestly though if you want to end it quick and fast hit him with your palm straight into the point between the tip of the nose (between the eyes). It will stun him and possibly defeat him, and it's really easy to pull off. One thing about it, it has to be done in the beginning of the fight and not in some later part of it. Otherwise your aim will be slightly off and you can hit him in the eye really hard. And while blowing off some steam while fighting a guy is OK (in my book) crippling him for the rest of his life is not.
I'm suggesting this because since you said that he is a big bad bully he is probably stronger and bigger than you, because of that you can't get up to a situation when you "wrestle with him".
Oh and forget about trying to kick him. If you are not trained in any form of martial arts your kicking will probably not be very effective and only get you exposed to an attack (possibly to groin area), because of that use your fists to continuously damage one of his areas.
Good luck on that fight. I personally never start a fight but if I have to, I usually win (never really, lost one time it just ended up with a tie).
PS. Last thing I forgot to mention. Don't hold yourself back. If you need to hit him, hit him hard, no pussy fighting in real life.