No, no, no, no.
Not until you can, at the very least, say I am an expert in not-safe-for-work.
- Why should we judge what is considered "safe for work" for someone? What would be the specific criteria for adding this tag to a question?
- Why can't the same content be "safe for work" in some settings and "not safe for work" in others? (Think private office versus open floor plan, for example.)
- Why is someone browsing the site at all in such a setting?
- In what situation would someone want to find questions that are "not safe for work"? (A major use for tags is searching for questions.)
- Who would be following such a tag? (Similar to, say, biology which has 9 followers, or terraforming which is followed by 2 users, or apocalypse which is followed by 7 users, or the 8 users who follow space.)
Don't get me wrong, I love the fact that this site has a lot of active users and a lot of visits. But when you are at work, you are supposed to be doing what you are being paid to do, not leisurely browse Stack Exchange. I can easily imagine settings where browsing Physics, Biology, Programmers, Stack Overflow, Server Fault, The Workplace, Electrical Engineering and what have you is relevant to the task you are supposed to be doing, but I am having a very hard time imagining a setting where browsing Worldbuilding is relevant to what you are being paid to do, and even more so such a situation where having a not-safe-for-work tag would add anything useful.
We get this type of suggestions repeatedly: using tags for things tags are not meant to do. Generally speaking, meta tags is something that we should avoid. I was a proponent of the science-based tag originally, which didn't pan out very well, and now we have another one (hard-science) which seems to me to quite possibly be going down a similar slope: answers taking liberties the tag is supposed to say they cannot.
Each question is limited to a maximum of five tags. In between the meta tags we already have (reality-check, science-based, hard-science; which are not uncommonly combined) that already puts serious limitations in place on the meaningful tags that can be added to a question. I tried a suggestion to rectify this somewhat, which didn't really fly with the community. It isn't at all uncommon today to see questions that are tagged reality-check science-based plus something else. If you add a not-safe-for-work tag, you're already up to three out of five tags before you have even stated anything useful about the question's topic. That does not make the site any more approachable or make it any easier to find the content you are looking for.