Wifey B: Until recently, most acronyms were just shortened ways to say things. Who wants to say North Atlantic Treaty Organization when you can just say "NATO"? Or National Aeronautics and Space Administration when you can say "NASA"? How often do you say Internal Revenue Service instead of IRS?
Then along came chat rooms, which are mostly dead now, but they developed some of their own language. It provided very convenient ways to react to things said. LOL was the first. Someone says something humorous, but they can't hear you laugh so you "LOL". Then several others to show more laughter such as "ROFL" and then "ROFLMAO" so even degrees of laughter.
Now we have texting and the desire to save keystrokes. I can't bring myself to use the extremes and type something like "I hope 2 C U soon." Frankly, many of them don't save that many keystrokes. 2 vs To. 1 keystroke.
And along came twitter with 140 character limits so then people really went wild finding ways to reduce characters.
Now back to the early LOL's and such to express emotions, along came smilies, which I may have been known to use once or twice
and now Emoji's have become big. They like smilies and like lol are attempts at including emotion. One of the biggest issues with typing online is that the emotion often doesn't accompany the words. You can't see if the person was serious or joking? You don't get a tone.
Now, we don't have emoji's here so stuck with just smilies. However, look at the difference between these two typed phrases:
That's about enough of your crap.
That's about enough of your crap.
When I use acronyms I do try to tailor to the audience. If one was texting or on twitter or in a chat room SMH would be understood, but here if I want to say "Shaking My Head" I use
So, the OP (note how acceptable OP is here just as PO is, but newcomers are often confused by them) used SUP, which has become a widely known term, but not with this audience and so a translation was needed. NBD (No Big Deal).