First, I would like to say there's nothing wrong with wearing a collar or anything to school or anywhere for that matter. I (no joke) used to wear a fox's tail when I was younger and walk around my neighborhood with it, it was a tail that you stick in the back of your pants and you can see it hanging down from the pants. People looked at me differently so I know how you feel.
I personally think that if you wan't to wear it, go for it! Don't be afraid of what others say because they are just jerks that are trying to put you down so they can feel better about themselves, trust me, I know; people like that used to make my school life a nightmare, so you're not alone. If they are interested and are asking you about your collar they will listen to what you have to say instead of trying to change the subject.
People that don't get the furry community or ignorant to the fandom will mostly look at the bad side of things, take video games for example, any sane person would know there are no links to games and real world violence, and yet people that don't understand games or ignorant to them will think the opposite because they what it to be bad and will only think bad things of it.
What I'm trying to say is people that don't understand something and won't take the time to understand it, they will think bad about it just because they don't know much about it. If you want to know how to get people off your back, there are no easy ways, trust me, I've been there too; but what I would do is just ignore them or try to hang out with some of your friends. (remember, there are strength in numbers)
With that said, I'm not saying get into fights, what I'm saying is that with more friends around you, it's less likely that you'll be intimidated by jerks like how you mentioned on how they act (I'm not saying that you are intimidated by them I just thought I'd mention it), I know it's easier said than done but as I said before: "There are no easy ways". In any case, I hope this was helpful and if you would like to talk further, just ask or PM me. If you like, you can add me as a friend on here so we can keep in touch.