Hi, English isn’t my mother tongue so I was asking myself that question since I first encounted a w/… Back then I was like: “What tf does ‘w slash’ stand for?” And when I found out I was like “How, why, and is it any intuitive?” But I never dared to ask that until now
I know this isn’t an answer on the topic of the history of abbreviations, but I found this page to have a useful list of abbreviations with the foreign speaker in mind.
they forgot kys :(
Kiss your stepsister?
keep yourself safe :)
Kind young soul
Kiss your sather