Mistake \Mis*take"\ (m[i^]s*t[=a]k"), n.
1. An apprehending wrongly; a misconception; a misunderstanding; a fault in opinion or judgment; an unintentional error of conduct. [1913 Webster]
Infallibility is an absolute security of the understanding from all possibility of mistake. --Tillotson. [1913 Webster]
2. (Law) Misconception, error, which when non-negligent may be ground for rescinding a contract, or for refusing to perform it. [1913 Webster]
these are far from mistakes and as much as i make you rage you can probably admit it to yourself (at least) these are on purpose.
i see no point in typing differently on a forum then i would ingame in the middle of a battle(in a rush, between jumps), just because it stays here doesnt mean you have to spellcheck and fix the obvious time-wasters that are capitals and apostrophes...list goes on.
if it helps you with your insecurity, go ahead. but i seriously dont give two shits and you most certainly wont ever see me type the whole word "because"

oh and dont misunderstand, for the people who always type perfectly without any slang (everywhere) then good for you
ontrollpic: what does your post have to do with the subject of the thread (dark collosus getting owned by monks and fires and raging about it) does your post have?
edit: its quite cute that every post of yours before the one pointing out slang/purposelybrokenwords almost all contain at least 1 "mistake"
