Could someone please explain to me what ...

Could someone please explain to me what it matters if I change my twitter avatar to a shade of green? Apparently this is going to make a difference to someone in Iran, but I have my doubts. I have seen a few people I follow on twitter doing it and noticed a few tweets about it.I just can't understand the damn relevance. The people of Iran don't care, they aren't looking or watching and the green avatar you are now sporting is not going to change the world, in fact I think that these green avatars are way to appear cool. And it bugs me.It might just be my opinion but that's OK with me. It just gets under my skin when I begin to feel guilted in to doing something as meaningless as changing the colour of my picture on twitter to a shade of green.