Not to nitpick, but “straighten” is a verb, so “up” is an adverb, not a preposition.
It’s not functioning as an adverb or a preposition there. It’s part of the phrasal verb “to straighten up,” and is just a particle. I would call it neither a preposition nor an adverb as it’s not fulfilling either of those roles.
My particular pet peeve is people writing “the worse” instead of “the worst”. E.g. “This is the worse hot dog I have ever eaten.”
If we are talking opinions, I think that moves like artificially trying to collapse cases (I = me, who = whom) or proscribing the subjunctive in clauses that are clearly subjunctive or might be and the mood makes a difference in meaning, while they do not impoverish the language, exactly, they make your writing less clear and harder to parse.
As a wordsmith, I absolutely hate the singular “they.” It makes any sentence awkward to read and even more awkward to say.
We need a better gender-neutral pronoun. I suggest that to he/him and she/her we add sha/sham. Or something equally new and easy and mono-syllabic and words like that.
Truly, that’s the wurst.
How about keeping it plural: “That person is shabbily dressed. They should be ashamed of themselves.” / “The man took an awful blow to the head. They were kept in hospital overnight for observation.”
I decided to come down one way or the other on that. First, I determined that I would write it OK because that’s the original. But I didn’t like how those little clumps of capital letters looked in my writing, so I’ve switched to okay because it just looks like any other word. Others can write it how they like, of course.
I think it’s regional. I use both, often indiscriminately, but generally speaking, waiting for is just a statement of fact. I’m waiting for John. But I’m waiting on John is both a statement of fact and an acknowledgement that John’s not going to be ready to go in the next minute or two. Either he needs to hurry the hell up or he doesn’t get off work until 8, and it’s only 7:45.
You’ve likely been using it your whole life with near-perfect clarity.
Pronouns are a class of words that strongly resist change. That’s why ours still retain an archaic gender and case system that isn’t really found anywhere else in our language. That’s the main reason I’m against neo-pronouns like xe–they’re just never going to catch on with the general public (IMO, of course). They is the best candidate for a universal gender-neutral pronoun.
Meanwhile, it sounds perfectly natural and normal to me. I don’t particular like any of the neologisms used as substitutes. If they were used enough, I’d get used to it, but they still sound less preferable to my ears than the singular they.
Huh - yeah, “by accident” is the way I’d expect to see it, though the comparison to “on purpose” makes that a somewhat silly distinction. We can omit it entirely by just saying “deliberately” and “accidentally” 
When you are queuing up for something, are you IN line or ON line? I never heard “waiting on line” until a few years back but it seems to be somewhat common.
Say you’ve got a pencil. You keep trying to sharpen it, but it’s no use. Pretty soon, that pencil is just a dull old stub of a thing. It’s useless and sad. Sure, you could keep it around to dig the larger Cheeto crumbs out of your keyboard, but you really ought to toss it out.
That’s whom. There’s nothing artificial about its long-predicted demise.
I was taught “My friends and I”, with “I” always last, because it’s polite. Did my teacher lie to me?
One not mentioned that bugs me is the “positive anymore”. It just seems so wrong.
I say “waiting on line,” but that is a NYC/LI regionalism. If you hear someone somewhere else say that, good chance they are originally from the NYC area.
No, “My friends and I” being correct has nothing to with etiquette, it’s grammar.
How you figure?
Because “I and my friends” sounds awkward to my ears. Still better than “Me and my friends”, which is obviously grammatically incorrect. IMHO.
“I skipped my morning walk today.”
Did I increase my daily exercise or fail to perform it?
Ego et rex meus ?
Quirk mentions a couple of times that it is considered “polite” (in English!) to place 2nd person pronouns first and 1st-person pronouns last.
You could make the argument that it’s ungrammatical in your own personal idiolect, but that’s as far as it goes.