I may need this.
When I was in college in the mid-1990s, I kept a “Bent Offerings” newspaper cartoon on my bulletin board. One person was scrawling “I before E…” on a wall. Another was correcting a menu, muttering, “It’s Brussels Sprouts, not Brussel Sprouts!”. A third was examining someone’s T-shirt, disapprovingly asking, “Is that how they taught you to use an apostrophe?” The strip was captioned, “Roving Gangs of Rogue Proofreaders.”
Yeah, this sounds like a good bet.