I think this song is about the teenage stereotypes. According to ignorant adults, all teenagers are either violent, vicious, or drug addicts. When they see teens that don't fit these prejudgements [goths, emos, etc.] they don't know how to respond, except to try and fit them into one of those categories. That's what the line "darken your clothes/ i'll strike a violent pose/ maybe they'll leave you alone, but not me" is about. When you don't understand something, you stay away from it- fear of the unknown.
You could also say it's about teen violence, which I think the song was originally written about. I feel that mcr is trying to say it's better to wear dark clothes and not fit in and scare people, than to actually be violent because no one gets hurt.
Mcr forever.