Where and when did this “makes me feel unsafe” thing start?

"But it’s such a common complaint that one hears it from across the political spectrum these days, in a loud chorus of whining victimhood, from gay students who object to proponents of traditional marriage, and from Christian students who object to nondiscrimination rules meant to protect gays; from Muslim students objecting to pro-Israel speakers, and from Jewish students objecting to anti-Israel posters. Just today I learned (via Hans Bader) that Oberlin, supposedly one of the great liberal arts colleges in the world, has been in a tizzy because of a speech by the rather mainstream conservative feminist Christina Hoff Summers, which supposedly made students feel “unsafe” well in advance. And so on. In no examples that I have seen has there been any actual threat or prospect of violence against the students complaining that they feel “unsafe.”" Being exposed to other viewpoints might make you think. Thinking is hard and might cause you to feel uncomfortable.
Where and when did this “makes me feel unsafe” thing start?
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