Oh yes, it does drive me crazy when people use incorrect grammar. I suffer from proper-grammar-sensitivity, (similar to the 'swipecard disability' I also suffer with at the checkout) These days, even professional signage can be gloriously, stupendously incorrect. And few people seem to care or even notice! Aargh! My pet hate? Misused apostrophes. I once saw this cartoon and burst out laughing, because it is exactly how I feel as I drive around the shops.
Now, I am the first to admit I make typos. All the time. Who doesn't? The key is proofreading and editing your work thoroughly. Kids laugh along with me when I read out their work to them, exactly how its written, with hilarious mispronunciations and all.
Grammarly.com is a great website which seeks to address this alarming trend in society - the demise of proper language use. I always say to my reluctant students; "Some day it will be absolutely vital to you that you are heard and understood. Don't be one of those people who is interviewed on TV who says something like, 'ah, yeah, and er, and then it, yeah, um, you know, it sort of happened.' Learn to express yourself properly. People are much more likely to listen to what you have to say if you are clear, concise and use a decent vocabulary."
Of course it takes more than a pep talk to achieve this! Particularly with some boys, who prefer grunts and gestures to actual words.