I think "K"
used to be the favored text-speak abbreviation of "okay" but by the time I started remembering to use it, my DS told me it had morphed into a version like the Disgust character graphic up above.
Then one time, I tried to text "OK" instead and my phone autocorrected to "OKAY" and he asked my why I was shouting.
Now, I very carefully type "okay" in small letters, or send a checkmark emoji.
I
think it's still OK to use to separate sentences (though kids will often use a line break instead) but I've been trying to remember to leave it off the actual
end of the text since I found out it messes up the tone. I ended up getting this book from the library: