It's not just uppercase lower
case, it's butchered spellings of words to make them as
difficult as possible to
read.
(A normal conversation from me and my "azn cappers")
Them:
aYe!
Me: Hi.
Them: h0w aRr y0oH dOin?
Me: I was better, but know I have to
read your shitty ass typing
Them: aH hElL nAw yOoH dInT jUsT
sAe dUt