Well I screwed up tonight
OP, I think that the demands about how you speak are probably related to a real inability to cope with problems understanding people -- my guess is that he truly believes that if other people could explain with enough detail/precision/concrete-ness (or whatever it may be, in his mind), he would never have trouble understanding others. So it doesn't matter if he actually understands what you say or not....if there is any vague-ness at all, it is upsetting to him because he thinks it is the way other people speak that is the only real problem. If he makes demands about how you speak only with things that he does understand, I would bet it is probably because those are the only things he can confidently see all the parts of (all the parts spoken and unspoken...if he doesn't understand something, he can't see all the parts so he wouldn't be able to tell you what you have to say for him to understand) and/or has the language to talk about.
My suggestion is that you make a deal with him to always try to give him the details/clarification/explanation he wants, so long as he asks questions instead of demanding. So, basically, you would promise to always answer his questions (to whatever your limits are for repeating yourself, anyways -- but make these clear from the outset) as long as they're questions. So, if he wants to know what "by the couch" means, he has to say, "What does by the couch mean?" rather than "You have to tell me what 'by the couch' means." If he doesn't come up with questions of his own to replace demands, or if there is any chance he may not be able to, I suggest offering him verbatim scripted ones.
Also (something to think about:), if he appears to have better language and communication skills than he actually does, people may not believe him when he genuinely does not understand things, and may not answer questions or explain things (may even mock or deride him or his questions, or get upset with him for no apparent reason) when he is genuinely unsure or completely at a loss about what is being communicated or what he's expected to understand -- he probably doesn't understand why and can't tell which questions people will answer versus which ones they won't, when people will be upset with him versus when they won't, and if this has happened enough times (even if doesn't happen all the time), may have come to automatically anticipate every situation involving him asking a question, not understanding, or wanting other people to speak more precisely or clarify as threatening or a fight.
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"Coming back to where you started is not the same as never leaving." -- Terry Pratchett, A Hat Full of Sky
Love transcends all.
To follow up on what has just been very well said and to give a fairly concrete example of the assumptions that can be Made about understanding my daughter who has a very extensive and apparently appropriate vocabulary, and reads voraciously when we recently moved house having helped pack some boxes wanted to know what happens now she truly despite having read many times about people moving house and having helped pack boxes did not know what removal companies did . She was not joking but anyone who did not know her would have thought that a fourteen year old saying such a "stupid" thing had to be . Advances in some ways linguistic skills can leed to problems I have stopped assuming she knows what is going on and now routinely ask if she has any questions
Funny you say that because I have had times where I would be at work at my old job and my office clerk would tell me where something is. I would go to that spot to get it and not see it so I would look for it and not see it. I would then think. "gee maybe he didn't mean it literally, maybe he meant around here" so I start looking around there only for him to get mad at me for "not listening."
I often felt I was getting punished for trying to be abstract and read between the lines only to screw up. But yet if I looked in that exact same spot, he would still get mad at me for "not using my common sense" because he meant the surrounding area. So I didn't know which one he would mean because it felt no matter what I did, either way was wrong.
Heh my wife does this to me, well she doesn't get angry at me but she will tell me to bring her the curling iron that is on the couch. I will go to said couch and look and look and not see it, tell her, and she will come and glance at it say look there it under the computer desk I MEANT near the couch as in the same room.
I wonder if NTs automatically know which one and I wonder if there are social cues they read to know the difference but we don't see that so it's a guessing game for us and people who are not understanding get mad at us about it because they assume we didn't use our common sense.
I don't think the average NT has any magic way of knowing or not knowing, but the average NT will have less of an expectation of precision, and I think THAT is the important point. The NT world generally accepts that language can be loose and that people can misspeak; dealing with all that and organically adjusting to the other possible connections is basically a normal part of life and communication. It wasn't until I dated a lawyer that any of my imprecision ever became an issue, and for him it was more that he was used to harping on details than it was that he wasn't able to figure out what I meant. At least my time with him proved to be good practice for having an ASD child!
As for that old boss - sounds like he was just difficult. There are definitely people you can never win with, and you can't let them get to you.
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Mom to an amazing young adult AS son, plus an also amazing non-AS daughter. Most likely part of the "Broader Autism Phenotype" (some traits).