Now that my rant is over, I should mention that not EVERY school teacher, principal or administrator is a mindless zero-tolerance automaton.
My youngest kid has a t-shirt with Chuck Norris holding an Uzi, and he wore it to high school probably a hundred times. He also wore a t-shirt with some Halo/XBox game fantasy symbol/something that features two large crossed rifles.
He never had an issue wearing either, and this is in Evanston, IL, home of radical leftism, home of the Violence Policy Center, one of the original handgun ban cities, and a "nuclear-free zone".
However, zero-tolerance did get my son booted out of junior high for five days. He had a clear plastic airsoft gun stashed in his backpack, which was going to be used to fight an airsoft battle at a friend's house after school. My son's reasoning was that if he left it at home, came home after school to get it, and then went to his friend's house, it would already be time to come home for dinner.
It so happened that he fell down during gym that day and broke his jaw, and had to go to the hospital. When a teacher went to get his backpack, the airsoft gun was found.
I met with the principal and vice-principal, and agreed that my son should not have brought the toy to school. Like it or not, rules are rules until citizens are willing to change them.
Their attitude was that, yes, rules are rules, but it was a stupid rule for not allowing school officials to exercise individual judgement on a case basis (in this case, an honor student who had never been in trouble).
They scheduled his five-day suspension to coincide with the days he would be in the hospital for surgery and at home recuperating.