I know this sounds melodramatic, but WHY ME?

We have a close group of friends. But they always gang up on me. If I have a disagreement with one friend, they all back her up. If I say something to someone, they get mad at me, but if a different girl in the group says it, it's fine. For example, my friends asked, "Should I leave my hat on or off?" and I said "Leave it on." because she had hat hair. So she gets really mad and says I told her her hair was ugly. Then, another friends comes up and say "Woah, got some hat hair?" and she just laughed. This happens really often. I don't get why I am the victim because I'm the kind of person that stands up for people (and myself). Why am I the one they pick on, and how do I get out of this position?