No, you will not be arrested for tresspass (at least, if they are following the law). Cohen v. Califorina specifically deals with this, where Cohen's Disturbing the Peace charge was overturned after the Supreme Court ruled that a t-shirt with the phrase "[Four Letter Word that Rhymes with Duck and starts with the letter F] the Draft". To spare you the full read of the decision, it can be summed up thusly: First, states (California) cannot censor their citizens in order to make a “civil” society. Second, knowing where to draw the line between harmless heightened emotion and vulgarity can be difficult. Third, people bring passion to politics and vulgarity is simply a side effect of a free exchange of ideas—no matter how radical they may be.
Roth v. United States famously decided to not define what merits obscenity beyond "I know it when I see it." which basically states that obscenity laws are passed at the lowest level of government, not nationally. What is obscene to a small mostly elderly conservative Christian town in rural Florida is "meh" to Los Angeles.
There are a few SCOTUS decisions regarding school speech but these basically are with regards to the School's role as a disciplinarian and still would not catch ire with the Courts if you were to wear a political statement such as that. Tinker v. Des Moines Independent Community School District held that the school could not suspend students for wearing black armbands to protest the Vietnam war, but speech that was disruptive and school newspapers could be censored (so long as they were the product of journalism classes and not a "community forum". Actual community News Papers (most colleges) cannot be censored.).
In all matters of speech law in the United States, the burden of proof is on those seeking to restrict speech, not the speech maker, that the speech is not protected under the First Amendment. Suffice to say, Speech is Free Speech until proven otherwise.