You should bring to the attention of the school the case of Tinker v. Des Moines Independent Community School District, where it was ruled that students have a constitutional right to free speech in the schools. They tried to suspend kids for wearing black armbands in protest of the Vietnam War, and the Supreme Court ruled that the school could not limit their political freedom of expression. So if you're trying to wear a blunt costume to protest the tyranny of the War on Drugs, you should have the constitutional right to do that. I doubt they'll listen to you, but it's worth a shot.