There are certain words that, when misused (or used at all), are some of my biggest pet peeves!
1- "Nother" IS NOT A REAL WORD!!! In fact, I think I die a little inside every single time I hear the phrase, "...a whole nother ... If you are referring to "another" something, great! I'm thrilled about that! However, as I said before, nother is not, in and of itself, a word.
2- Your/you're. This drives me to drink!!! Well, I don't drink, but it would drive me to it if I did! This is so EASY!!! Allow me to explain.
"Your" is possessive. If something belongs to you, or you are referring to something that belongs to someone, this is the appropriate spelling.
"Your sister is very pretty!" See how this works? The sister is yours. Not you are's.
"You're" is the combination of "you" and "are". It should be used when shortening and combining the two words.
"You're very pretty!" This could be written you are very pretty, but would not be your very pretty. That's just awkward.
The worst I ever usage I've ever seen was on a film set in a boy's locker room etched into a locker it said, "you'r dumb." Right kid, good luck with life...
3- There/their/they're. All I can do with this one is sigh.
"There" is referring to the location of something. "Their" is possessive of something. "They're" is they and are combined.
I know there are others, but seriously I'm exhausted and annoyed and I don't see how going into it any more will help. Most of the offending parties don't even read my blog! There should be a grammer help zone for some people. I do feel better now though. Hooray for that! :)