Man am I glad I went to school the time I did... the only things that were banned from our dress code were clothes that were too revealing, had blatant cuss words on them, and... that's it.
There were guns n' roses, tees everywhere. As well as every other 80s and 90s rock band you could imagine. I myself had a T-Shirt with crosshairs over Saddam Hussein's face, right between the eyes, with the subscript "Public Enemy Number One". Er... this was Gulf War I, of course.