People always walk up to me and ask in this really, really rude tone stuff like, "Why do wear so much eyeliner?" "Do you ever not wear black?" "Why are you so emo?" and the one that really gets on my neveres that people ask all the time is "Do you cut yourself?" Why do they fucking care????
Just have a handy response like: "Are you ever not a douchebag?" or "Are you really so boring you have to ask me stupid questions?" I used to have bright pink hair last summer and people said stupid things to me all the time.
I guess they think it doesn't fit you very well so they're curious why you're doing those things. And if they are friends of yours then of course they care if you cut yourself. No one wants their friends to do such a thing because it's a bad sign.