People that think a spellchecker is a great substitute for, perhaps, learning to spell. Computer programs are depressingly literal-minded, and the lack of a wiggly red line doesn't mean it's the right word. It's down with wrong words, as long as they're spelled correctly. It makes me wonder what the spellchecker does find in what they type -- probably everything, before they change it to please the oracle and assume that they now look literate. Pet peeves include:
L-O-S-E. "Lose." Lose your shoelace, and you can't find it, unlike "loose." When you loose your shoelace, you trip over it. The two are pronounced differently also, so they're not hard to tell apart. An alarming number of people use 'loose" for both, and when some well-meaning spelling Nazi such as myself corrects them, accuse me of being a spelling Nazi then go on using "loose."
"They're," "their," and "there" are different words, mean different things, and aren't interchangeable. [I stopped using quotation marks in this post here because it makes trying to decipher this crap lots funnier. -- S.] The hat is over there, not over their. It's their hat, not they're hat. Again, not interchangeable, and not knowing the difference makes you look stupid even though your spellchecker tells you you're very special and doing everything right. Or is it your special and doing everything right? It's one or the other, or maybe its one or the other, right? (Observation: The checker hasn't found anything wrong with what I've typed so far, therefore it must be all right, alright?)
Its is the possessive form, i.e. some thing that belongs to it it its thing. It's is the contraction of it is. It's way is what its in. Its in it's way. Or is it it's in its way?
People can use the correct pronoun but in the wrong verb tense, i.e. subject and object pronouns are different in English. Which of these is correct? She gave it to he and I. She gave it to him and I. She gave it to he and me. She gave it to him and me. (Any choice except the last one means you have the clap, btw.) When in doubt, remember that us and him = objects, we and he = subjects. (Us and we are plural, that's the only diffence.) if you can substitute the singular or plural pronoun for whatever you're unsure of without it sounding stupid, you have the right one. In my example of a young lady giving the gift to remember her by, she is the subject and everyone else are objects. She gave it to us sounds right, but she gave it to we doesn't. If you can use us in a sentence, you can't swap it for he or I. Likewise, if you can use we, stay away from him and me. I will get a penicillin shot, not me will get a shot; also, the doctor will give me a shot, not give I a shot. I got into a stupid flame war on some message board when I joked about someone making this mistake four times in one paragraph, and got buried by an avalanche of boy-are-you-stupid posts that informed me it's where the word appears in the sentence - at the end of a sentence, you say him, but you use he at the beginning. Oh, good. If something falls in the middle do I have to count the words to find out which side it's on? That makes it easier for both you and I.
I have studiously avoided snarking on people that botch one of the above or something similar in posts here, because a) this isn't a very formal environment and we're not getting reviewed, published, or graded on what we do, so who cares, b) I'm really not an asshole about this stuff, if someone doesn't mind looking stupid (or enjoys looking stupid) that's fine with me (as long as they don't mind my opinion of them based on the available evidence), c) everybody makes mistakes sometimes, me included (I probably do, anyway) (joke) so it could be a trivial honest slip-up or typo, d) we have non-native English speakers among us, some of them amazingly proficient in a foreign language, some not, but I'm impressed enough that they make the effort to cut 'em a lot of slack, e) some topic drift or asides are inevitable, but I don't want to derail a discussion by joking about their writing and starting a flame war where I'm outnumbered by the opposition, and finally f) my jokes are quickly going to go way over their heads, and my hopes of spirited aerial combat in jet fighters are dashed because they know dogfighting is why they live in Alabama with pit bulls, and what the hell is this idiot doing with that airplane? It all ends up in the mudwrestling pit anyway.
HOWEVER, from now on, there will be one exception to my "suffering fools gladly" policy as stated in the last paragraph. (This counts as the Official Notice I'm legally obligated to give the populace, so in the future always consider me locked, loaded, and ready to fire.) I am going to be ruthless with "loose" and "lose." It makes people look the dumbest and they're exposing vital areas to my line of fire; it also doesn't happen as much ("is" gets used more than "lose" in normal discourse) so the thread-derailing tsunamis will hopefully be infrequent. The primary reason is I can keep the jokes about this one down to a level comprehensible to the 7-year-old mind and get as poisonous as I choose, while maintaining what appears to be pleasant, jocular banter. (Insert evil supervillain 'mua ha ha" type laugh here.)