Your first example is what I said (gender unclear/unknown), and your second example is proper use already (plural of he or she.) I’m pretty sure “could everyone take his or her seat” is wrong.
I admit the first one wasn’t a very good example. I’m getting tired, and it’s the first thing I thought of.
The second one, though, I wonder if anyone knows for sure, because now I’m second-guessing it.
Just about everyfreakingbody these days. It’s one of the few dialectical quirks that drives me up a wall. I’d guess you’ve heard it before, too, but it just hasn’t pinged your radar. Either that, or you’re a very lucky individual. Common usage would be in a sentence such as “Debra and myself will be hosting a dinner party this Friday.” It can be analyzed as an emphatic substitute for “me,” and that does make sense to me, but it still is like nails-on-chalkboard to my ears.
Uhhg. It’s douchey business-speak. Commonly seen in internal corporate emails. Justin Bailey is probably spared because he works in a library, surrounded by people who can actually read and write.
U r mi ho mi Sk teh R. Srsly
Punctuation will be soon lost in the tweeter fog. The SDMB will be seen as a quaint anachronism where fogeys still attempt proper spelling and sentence structure. And still fail at it, but no one else is going to even try.
This is the sort of thing up with which we are going to have to put.
Thru is replacing through.
Don’t worry. The Internet and texting will change everything in the future.
Nobody can make fun of people for bad grammar or misspellings anymore.
Or in the case of your example sentence, for “I”. 
As for singular “they” – it’s recommended in the Chicago Manual as of the 14th edition (says Wiki), so perhaps the whinging will finally subside. I hope so.
That is not an example of not using adverbs. That is an example of not using the ly suffix to change adjectives into adverbs.
Huh? “Aggressively” is an adverb, which should have been used in that sentence. The sportscaster didn’t use it. Therefore, it is an example of not using adverbs where appropriate.
Let me explain. Though the ly suffix is often used to change an adjective into an adverb, it is not absolutely necessary; some words are the same in both adjective & adverb forms (such as fast, more and aloft), and some adverbs don’t even have adjectival forms (such as perhaps and maybe. The sportscaster simply omitted the suffix, trusting that his meaning would be clear in context. This is a simplificiation of the language akin to using the same forms for the singular and plural forms of the second person pronoun.
I am aware of different adverbial forms, thank you. Here, though, I am not talking about adverbs that don’t end in “ly” or those that are the same in both forms. I am talking about the use of “aggressive” as an adverb. That, and nothing more. The sportscaster used the word incorrectly. I hear this same kind of error all the time. You suggest the sportscaster knowingly dropped the suffix, and I suppose that is possible. I however think it is much more likely that he had no idea of his error.
Double negatives are common in many languages. Maybe they will disappear when English speakers travel more.
I remember seeing ‘thru’ in US books from the 1940s. If anything, I think it was more common then than now.
The way English handles double-negatives is one of the few things I like about it over otherwise more logical and consistently structured languages such as Spanish. I hope this one doesn’t change.
“Could everyone take his or her seat?” is correct. It’s just awkward. When I was growing up in the 1950s, we didn’t have to pay any attention to the feminine forms. People usually said, “Could everyone take his seat?” But eventually the women got tired of being referred to as “his,” and they protested. Since everyone is singular, we weren’t supposed to change it to the plural they. That’s why grammar books added “or her.” Then some of the women decided to be sneaky and put her first. “Could everyone take her or his seat?” Well, we couldn’t have that. So more and more grammarians are turning a blind eye to writing “Could everyone take their seats?”
By the way, Cisco, English is very logical when it says, “We have no bananas.” What is illogical about that? It would be illogical to say, " We don’t have no bananas, yes?"
One shift that is in progress: All right is becoming alright. I see it in movie captions and I just hate it!
Something I saw on TV today in big letters. It made me laugh out loud and wonder what my 96 year old mother would think that it meant: WTF?
2109 … the year the Great Serial Comma war started.
I’ve heard “their” all my life so “his or her” just sounds really akward to me in this sentence. I guess “everyone” is a collective singular? I never really thought of it that way.
Why are you addressing this toward me? I just said I agree with the way English handles double-negatives.
The statement plagued by ambiguous pronouns. Even “Could everyone take their seat” is ambiguous. For proper clarity “Could everyone take his or her own (respective) seat?” Realistically we have a better tool for referring to a group being addressed than a third person collective, I prefer “Could you take your seats?”.
And for you “y’allers” we already have a second person plural. We don’t need a redundant pronoun.
What is it?