KK. Except that it actually comes from at least as far back as aviation radio shorthand of the early 90s, and more likely goes back beyond that. It's been a Air Force equivalent of "aye-aye" for decades. K is "acknowledged," and KK is "acknowledged and confirmed," similar to the older "Roger, Wilco."
The story I got in my early AF days was that it was old Morse Code shorthand, though I've also seen claims it came from the airline industry reservation system. I've never before heard anyone claim it comes from "kiss kiss," and the
wictionary entry makes no such claim. I think you're just making strange assumptions based on the flip-phone texting culture you grew up with, Broseph.