Back in the reddit days I was pretty active on the Back to the Future subreddits, and one day an excited young man posted his new BTTF tattoo; a big colorful depiction of the 88 from the time machine's famous digital speedometer, glowing orange numbers on a black background, in a very visible spot on his arm.

I sent him a DM to the effect of "I get what you're doing as a BTTF fan, but you should be aware that if you're not a white supremacist there's a good chance that tattoo can be gravely misinterpreted by people who see it out in the world" and linked this page on the number's use as a hate symbol. He replied with an "OMG, I had no idea! Thanks for telling me!" message, deleted the tattoo post, and soon afterward deleted his whole reddit presence. I sometimes still wonder about that guy and how he's managed.