I wasn't planning on doing a social justice metaphor today, but I happened along one that seems to have instantly caused several people an epiphany, including the friend I first used it on.
Often when explaining linguistic harm to people we have to resort to metaphors. Many people who can only be insulted or offended, but cannot really be harmed by words (cis het white guys in particular). They don't understand the difference between offense and harm. A dead baby joke might be offensive, and I would leave if they were told around me, but no one thinks they would be okay to tell at the wake of a baby who died from S.I.D.S. They would drag the parents through the experience again and cause people actual mental and emotional harm.
Words don't have to rip your flesh from your bone like you're an X-man villain to do "real" damage. That is a sophist and immature outlook that everyone should get over when they retire the "Sticks and stones" poem for the realization that the N-word is not just your run of the mill taboo curse word.
The way slurs or insults cause splash damage (like "bitch" or "gay") go beyond just the people they intend to insult and cause more than just "offense." They remind people of the less-than-fully-human status they hold in our society because their very identity is associated with "bad things." Further they reinforce the negative stereotypes that serve to other and dehumanize. Some people endure this constantly. Which does measurable harm by statistical bellwethers in everything from blood pressure to heart disease to average salary.
Usually the metaphor that is used is the "death by a thousand cuts" metaphor. That is, no one slur or insult is the coup de grace. Men (for example) can be insulted by being called names, but they get over it pretty quickly, and no insult a man can hear really serves to remind them of the way they are treated as second class citizens. Women on the other hand are the subject of a VAST array of insults that tie negative characteristics towards feminine traits (bitch, cunt, pussy, ...like a girl) and serve as a reminder that they are never going to be seen as fully human by society at large. No single insult is fatal, but a thousand cuts all cause bleeding.
Today I found quite a bit of traction with the idea of damage over time spells, which may work if whoever you're talking to is into video games or roleplaying games. One damage over time spell...no biggie. You get immolate, corruption, curse of agony, serpent sting, and vampiric touch....you're in trouble.
Here's what I said: "It's like a D.O.T. It might not do that much right when it first lands, but it keeps working. It keeps reminding you of your status. And it keeps tying your identity to something people think is A Bad Thing™ If you have 50k HP, you don't think much about a dot that does 3 damage per tick (that's not even enough to cancel out your healing), but you might not be so blasé if the duration was an entire week....and you get ten or fifteen of these DOTs slapped on you every day....sometimes just for walking down the street....and that's ten or fifteen per marginalized identity, so a queer woman of color would deal with racism DOTs, sexism DOTs, and Heteronormative DOTs.
And then you come along and tell them not to be so angry that you just used yet another area-effect DOT "as a joke," or used a word that means THEM to insult to another person, or dropped a slur and informed them that you don't see what the big deal is."
I can't speak for everyone, but this particular gaming nerd insta-GROKed the concept.