Question: What Is 'NSFW'? What Does NSFW Mean?
'NSFW' is a warning for an email subject line. It means 'not safe for work' or 'not safe to be viewed at work'.
It is used to warn the recipient to not open the message at the office or near young children, because the message contains sexual or repulsive content. Commonly, NSFW is used when users like to forward lewd jokes or crude videos to their friends. Considering that millions of people read their personal email at work, the NSFW warning is helpful in saving people potential embarassment with their coworkers or supervisor.
Here are several other common Internet abbreviations and chat shorthand