I used to be the little kid in school that bigger kids picked on. One guy kept showing of in front of other to gain respect bytrying to get me into headlocks. He did this several times and humiliated me. He would usually try to push me and get me to push him back and then it would always end somehow with him having me in a headlock and me having no clue to get out.
Then one day, I told my mom and dad

and they told my teacher who I saw yell at the bigger kid...
THEN IT GOT WORSE!
So about a week later I decided that there was NO WAY I was going to put up with this. The next time he pushed me, I was so mad, I screamed at him, and pushed his head into the wall as hard as I could. I contined yelling at him until I saw his read face and 2 feet of spit hanging from his mouth...
After that he got my respect. And I got others respect.
Basically dont put up with it and handle it yourself, as I can see you want to. And remember : anything goes.
The guys that want to fight you are probably gonna be guys that are stronger than you, so use any kind of defence or attack... whatever it be elbows, knees, footstomps or headbutts, hell if you have the oppurtunity to use a fancy technique do that!
As long as you get the job done.