What is the most annoying grammatical error a person can make in a forum post?

While gross grammatical errors irritate me, so do grammar nazis. I mean some of the hyperbole in here is a bit much. It's a forum on the internet for fucks sake. Who gives a shit?

its wen ppl tlk lyk dis dat it annyz me. I have somebody on my friends on Facebook and "shee tlks loike diis". I could go next door to her house and physically punch her in the face. Really pisses me off.

B- It's lazy and unthoughtful.

Me Not NOU On How 2 Rite