Fail to put two spaces after a period, question mark, or exclamation point? Seriously, ever since using the computer in middle school, we've always been taught that this is the correct and professional format, and I've stuck with it the rest of my life. I mean, I don't usually care about this stuff, but what bothers me is people are such grammar Nazis to the point they'll put quotation marks around and italicize titles, writing their posts like some kind of biography or novel, yet even the people who try the hardest don't seem to remember to put two spaces?
It doesn't really bug me, I don't care how other people wanna type, but I just think it's weird how I'm basically the only person who does it.