It annoys me when I find most people don't know certain things about the language they speak that they really should know! I see it and hear it all over the place.
The first thing that annoys me is the improper use of "to" and "too". In fact, seeing the word "too" is very rare it seems. The word "to" usually refers to a destination. For example, I could say "I'm going to the store." I could also say "I need to do my taxes." The word "too" refers to a number. I could say "There are too many birds crapping on my car." The word can also be used to substitute the word "also". "I am writing a book too!"
The second thing that annoys me is the improper use of "translucency" and "transparency". So lets get them straight. Something that is transparent is said to be 100% translucent. Transparent is something you can see through completely. Translucency is a degree to which you can see through something. Most glass is transparent, whereas a compact disc is translucent (if you don't believe me, pick up a CD and look closely at the bottom of it). So please don't call something transparent when it's really only translucent!
I'd love to hear what things annoy you about how people use the English language. Leave a comment!