People who still use 'txt tlk'.
There's absolutely no reason for it. The reason why it started is because when text messages first came about you had 160 characters and being 10p a message, you wanted to fit in as much in one message as possible.
You've got a full frigging keyboard in front of you, even on your phone FFS! No excuse whatsoever! You actually have to go out of your way to use 'txt tlk' what with autocorrect and that. And all you're doing is making yourself look thick. It's even worse when you see older people using it.