I've said it before, but I guess it's a bit weird since it's coming from me, but I sometimes consider myself to have anglomania. Despite whatever interests I have in East Asian entertainment, I do have a fairly wide palette for British Comedy, going back as far as Beyond the Fringe to the Catherine Tate Show.
Catherine Tate, as one of her characters, Lauren, says some of the most bewildering expressions. Having never spent any time in British high schools, or conversed at length with what I interpret to be a British version of valley girls, it's hard to say whether Lauren's lines are accurate to the sociolect, or intentionally awkward for comedic affect. (For reference, you may want to watch this youtube video, or perhaps a more relatable example here.)
The standard "yes?" is replaced with "alright?" as so:
A: "hello, Lauren?"
And the stranger one is replacing any affirmative with "isn't it though?" For example:
A: "Are you Lauren?" or "Will he be coming today?"
L: "Isn't it though?" (instead of "aren't I though?" or "won't he though?")
And queer as it is, I distinctly recall encountering similar pronoun hijacking in conversations with younger native speakers (say, born after 1985), but cannot remember a specific exchange.
What's more interesting is that I've also experienced this phenomena when teaching Japanese, most particularly in the case of a certain female student.
This student, whom we shall name Petunia, would answer every homework question with ～です, roughly equivalent to responding to every question in English as "it is ___". Almost like "isn't it though?", except that the response isn't a question. For example:
Q. "What time did Mr. Tanaka go to work?"
A: "[He left] at 7:00"
P: *"It is 7:00"
Q. "How did Mr. Tanaka and his friend go to the park?"
A: "[They went] by car"
P: *"It is a car"
Q. "Where did Mr. Tanaka bring Mr. Smith?"
A: "[He brought him] to the restaurant"
P: *"It is a restaurant"
etc, etc, etc..
Damned annoying to have to repeatedly tell Petunia that as handy as ～です was, it wasn't useful for most of the homework assignments. The way I figured it, she either was so rushed that she couldn't even mimic the verb form from the question, or her mental capacity was so low that Japanese grammatical statements requiring more than copular verbs were too much. OR, she just didn't want to believe me on the coincidental-but-irrelevant fact that one of her friends didn't like me.
Assuming these two specific incidents are any indication, there may be a more basic cognitive reformation in modern speech. So, it would seem that the default "it is"/"is it?" may be linked on a more pragmatic level than a grammatical one. (In the sense that "I, Tarzan; you, Jane" might be rephrased as "me -- it is Tarzan; you -- it is Jane".) Disturbing to my 20th-century ears, but maybe that's just me.
What sad times are these when people can't even keep two sentences together?