I was homeschooled till 8th grade. There was always this one mother fvcker who would fvck with me, and I let it go because I didn't have the balls. Even my science teacher pulled me aside and said "son you have to stick up for yourself." It's hard being a new kid in school though, I knew no one.
Fast forward to high-school, he tried doing it. Were in the stair well. I booked him, and smacked his hat off of his head and said"fvck you man" He basically told me something to the extent that all I had to do was stick up for myslef.
That was freshman year. Another time this other kid I knew from 8th grade ran his mouth at me in class like my junior year, Idk what he all said, but it was real disrespectful, something like how he beat me up in 8th grade, he never did. But I waited outside the class room for him. He was the last one out. I get in his face said something to him, then I head butted him (not to hard) and the back of his head hit the locker. he says "I'm not afraid of you." and ran off.
Like every one says learn how to fight. If you live in the U.S. and conceal carry is legal where you are, I would do that if you feel the need to protect yourself. I mean if its a group of guys, im not risking my life to prove I can fight. I'd rather put rounds down range.
Or, just go fight them, get your as$ beat. Go back again, let it happen again, and again. Eventually your going to freak them out, because they will think your crazy, people fear crazy.
If you come at some one hard and aggressive enough the first time, just the pure shock and awe will fvck them up.