It annoys the hell out of me when . . .
PeOpLe TyPe LiKe ThIs!- It's hard to read, and it's just stupid
When people don't use commas or spell the possesive form of you're like your! That's not how it's spelled!!
when ppl type lyke dis. omg ur sooooo cute and fnny! I luv u! that kind of stuf
AND FINALLY . . .
When people don't use periods and commas. Just punctuation in general. You can't tell when things stop and end.