I have just begun to notice people using "their" and "his" or "her" incorrectly. For example, instead of saying: 'One of the women has her appointment' , they say 'One of the women has their appointment'. It irks me at times more than others. Sometimes it's difficult to use any other word when speaking in conversation. It becomes a hassle to say "his or her" each time the subject's gender is in question, but I always appreciate the effort. When saying "Someone has her panties in a twist," most people say "Someone has their panties in a twist," which is grammatically incorrect.
I guess a lot of things in the English language are open to ridicule. It used to irk me when people said "I seen" instead of "I saw" or "we was" instead of "we were". I hear that a lot and it continues to bother me, but I can honestly say I think it's good on my part that I notice and do not emulate that speech. I am fond of using the English language correctly.
One thing that shows up most in writing is the difference between their, there, and they're. An overwhelming amount of people use those three words incorrectly. Also, your and you're and it's and its get misused.
I say if it's difficult to know when to use an apostrophe, make the two words into one. If you can do so, it's appropriate to use the word with the apostrophe. I was looking on my boyfriend's computer recently and found some invitations he had sent about a party. They said: Your invited. I cringed and prayed it was a joke. When I pointed out his mistake, my boyfriend was mortified that he had sent invitations to several people with such a blantant error. I constantly remind him, even if we are just chatting on instant messenger, to use the correct forms of words.
I loathe talking to people who insist on shortening words into sickening instant messenging abbreviations. I have even spoken with some people who use "no" meaning the word "know", which confuses the hell out of me. How hard is it to write the rest of the word? Or even scarier, do these people not even realize their mistake?