They also have sweatshirts, ladies cut T shirts, hoodies, etc.
Personally, I think it is probably best to put the words on the back. That way, people can read them without you knowing. They might feel less intimidated to do so if they don’t have to look at you head-on.
Some one told me to always have the words on the front. Then you are warned if someone is going to hit you. Nothing worse than being attacked from behind.
I think this like the toilet tissue issue. Let it hang in the front or back.