University of Michigan students called police the other day — because someone had written Donald Trump’s name in chalk.

No arrests were made. The episode is part of a nationwide trend of Trump supporters writing pro-Trump messages on sidewalks, stairs and other surfaces at college campuses, where fainting fits are sure to ensue.

When they could get no relief from law enforcement, the University of Michigan students took it upon themselves to erase the offending messages — including “Trump 2016,” “Build the Wall” and “Stop Islam” — while fighting through feelings of betrayal.

One student complained that there should be a special emergency number to call in such cases — one wonders how often students are really going to need recourse to an unwelcome-chalk-message hotline — and said that the administration’s inadequate response “perpetuates these really racist and hateful stereotypes that turn into violence and turn into students of color feeling unsafe on campus.”

Rarely before have a few scribblings been so traumatizing — and written not even in ink or paint or some other difficult-to-remove substance, but in the same chalk used to mark out hopscotch courts and write temporary promotional messages about sorority mixers and student theatrical productions. That chalk messages can be considered tantamount to a physical threat captures the crisis of free speech on campus perfectly.

What has become known on social media as “the chalkening” demonstrates how some college kids can’t be exposed to the simplest expression of support for a major presidential candidate without wanting to scurry to the nearest safe space. By this standard, a “Make America Great Again” hat is a hate crime waiting to happen. It’s not clear how any of these students can turn on cable TV or look at the polls for the Republican nomination these days without being triggered.

Pro-Trump chalking took off after the reaction at Emory University, where some students were reduced to tears by the messages and said they felt “fear.” Protesters gathered at an administration building and let loose the antiphonal chant, “You are not listening! Come speak to us, we are in pain!” This might have been an appropriate response if the kids had been tear-gassed, rather than seeing a positive phrase about a candidate who is supported by some significant plurality of the American public.

The president of the school, James Wagner, promised to review security footage to try to identify the perpetrators, and in a statement full of campus diversity jargon pledged, among other things, “immediate refinements to certain policy and procedural deficiencies” and “regular and structured opportunities for difficult dialogues.”

How about striking an even greater blow for diversity and asking the kids to get over seeing an anodyne political message that they disagree with? To his credit, Wagner himself chalked, “Emory stands for free expression,” a message that will evidently have trouble penetrating the formidable incuriosity of some of his students.

The reaction to the chalkening is a testament to the electric charge surrounding Trump. He is like the Washington Redskins of political candidates — so politically incorrect that some people can’t bear to see or hear his name. (The New York Times columnist Charles Blow actually refuses to use it.) This branding isn’t prudent positioning for a general election, but it makes Trump a perfect vehicle for provoking the other side, and it’s in that thumb-in-the-eye spirit that the Trump chalking is spreading.

The students getting the vapors over it don’t understand free expression or what it means to live in a free society, where you inevitably encounter people who have ideas and support candidates whom you oppose.

They hate Donald Trump. Fine. That’s reason to argue and agitate against him, not to seek protection from any contact with supporters of his, no matter how tenuous.

If they’re having a hard time handling this election cycle, just imagine how Reince Priebus feels.

comments.lowry@nationalreview.com