Ambiguous talk is just annoying!
Teenagers like to talk in slang - we all did it. And they are notorious for speaking cryptically and ambiguously - the hallmark of passive-aggressive behavior. As we get older, most of us tend to speak more clearly, particularly if you are in a profession which requires clear communication skills.
For example, pilots have to communicate clearly and succinctly. You can't blather on, on the radio, when the same channel is being used by dozens of pilots and traffic control. You have to be quick and accurate. And the results of miscommunication can be deadly.
For example, I was watching one of those "air crash videos" that analyzed an air disaster. A number of communication mis-steps occurred, including the air traffic controller misunderstanding the position and direction of the airplane (in a small airport in Corsica which had no radar at the time). The controller, for whom English was a second language, told the pilot to "descend, two-four-hundred feet" by which he meant, "descend, 2400 feet." The pilot dutifully set the autopilot "to 400 feet" and flew into the side of a 1500' mountain, killing everyone on board.
English can be a difficult and confusing language, particularly for those who learn it as a second language, and homonyms are a good example of this problem/ Another aviation video illustrates why the words "to" and "for" are never used in radio communications as they can be confused with "two" and "four."
So the air traffic controller says, "descend, 9,000 feet" and the novice pilot replies, "10,000 for 9,000 feet" which is technically incorrect, as it could be read as "I am at 10,000 feet and climbing to 49,000 feet" which is ridiculous, of course, for a pilot in the process of landing and 49,000 feet is beyond the ceiling of most aircraft. So the grammatically incorrect "descend, 9000 feet" or "climb, 12,000 feet" are more clear and concise.
In Engineering, Medicine, the Law and a number of other professional fields, speaking concisely and unambiguously is essential. A doctor can't say, "Nurse, hand me that gizmo!" An Engineer can't say, "We need an I-beam about yea long and about this thick!" Lawyers can't talk like Lionel Hutz as illustrated above, asking for a "bad court thingy!" Sadly, we are trained to speak clearly and succinctly.
And of course, we fail. In a technical writing class I took, I was told never to start a sentence with the word "And." But look, I just did! Oh, she said never start a sentence with the word "But" either. Oh, shit, I did it again. And never, ever start a sentence with "This is because..." This is because the reader is unclear as to what "this" refers to. And don't get me started on subject-verb disagreement!
There are lapses in judgement and then again, there is just lazy writing or speaking. Particularly when you are communicating with intimate friends, even a nod or a raised eyebrow can speak volumes. Or, as in The Sopranos, they often talk in code. "Did you do that thing with that guy we talked about?" "All taken care of, Tone!" But when such talk is used on outsiders, it becomes gibberish.
And that is why teenagers claim to be "misunderstood" by adults, because the slang and shorthand used between peers is just gibberish to outsiders. Of course, sometimes, this use of slang and ambiguous speaking is intentional, particularly by passive-aggressive people, who want to sow chaos and uncertainty. And people like that are quite annoying.
I have written about passive-aggressive behavior before. Sadly, speaking ambiguously and not having a firm opinion on things is taught to young women as a means of being coquettish and coy. Most men, however, find it annoying - and also a trap. If your girlfriend is constantly saying, "I don't know, you pick!" whenever you ask her where to eat or what movie to see, run away as fast as possible. No mater what you decide, she will regale her friends - in front of you - how you "forced her" to see a movie she hated or go to a restaurant that sucked. Life is too short for that nonsense. And no, being passive-aggressive isn't sexy or cute, it is just annoying.