It is common in online conversation among some Internet users to use a fictitious closing tag patterned after HTML: </sarcasm>. Over time, it has evolved to lose the angle brackets (/sarcasm) and has subsequently been shortened to /sarc or /s (not to be confused with the valid HTML end tag </s> used to end a struck-through passage).[20] Users of the website Reddit frequently denote sarcasm through the use of /s, as shorthand.[21] This usage later evolved into tone indicators.
Wow, I didn't know the /s had an origin story. Pretty cool.
I mean I can barely remember and hate using /s. at least it annoys me that things which to me is obviously sarcasm, cannot be seen as such on the internet. granted when hanging out and being sarcastic it was sometimes a win to get the double take or eh response.