Remember, NSFW is not an abbreviation for nude that somehow has more syllables. It’s shorthand for “If my boss happened to look over my shoulder when this was on my screen, would there be consequences?”
This is subjective, and depends on the boss and the job, of course. But many, many images that contain zero nudity are still very much NSFW (and sometimes, images with nudity aren’t!) Consider this.
just goes to show how young the population of the internet is nowadays. nearly everyone that was into the internet for real in the early 2000s knew this kinda stuff
