Decades ago, I was having lunch at my parents house. There was a newspaper on the table, unopened, just brought in. I looked over the top of page 1. Unfolded it, and there was a picture of a dead body in the street. It was a story about some conflict in another country (Bosnia perhaps). I'm OK with seeing that if I'm already reading about it and in the right frame of mind, but "not safe for lunch" really hit me that day. So much that I called the newspaper to complain about "being surprised with a dead body on the front pafe during lunch". I've never done that before or since. ;-)

As in, something nsfw is not okay for work, something nsfl is not okay fir life in general.