It's really hard to explain it, I remember someone using the word and then telling me what it meant about 2 years ago. I think the context that they used it in was in their relationship and their partner didn't want to be constantly asking for them to change, but they had the one thing that they didn't want him to do and it was to be friends with this other girl. I think they used the word like this: 'It was her [...], she didn't want me to be friends with blah blah'. The only way I can really think to explain the word is that I think it is sort of similar to 'one-off' but more specifically being about a specific one off that can't happen, almost like a request. The one thing that you don't want to happen or someone to do. Sorry, this explanation has been really bad. Thanks for your time.
It's a dealbreaker:
A term popularized by Liz Lemon from 30 rock which is used to describe the event which led to a breakup with someone or something
A deal breaker is ‘the catch’ that a particular individual cannot overlook and ultimately outweighs any redeeming quality the individual may possess.
You can see the term used this way in the following articles:
I believe the term you're looking for is pet-peeve.
This is defined by Merriam-Webster for English language learners as:
something that annoys or bothers a person very much
Hope this is helpful!
off the table is a term that means , in my words, that the thing described "non-negotiable by choice and notice"
Note, it is not "a thing" (your title) but a state. "Which things are off the table?" would be an important thing to want to know when starting negotiations.
Two parties in a contractual dispute in normal business agreement with many contingencies and mutual responsibilities might need to be renegotiated and responsibilities reassigned. In an office space lease there might be issues with signage and parking spaces and lease expiration and share of common area maintenance and representations about noise or if a promise was made to re-landscape the exterior or who was responsible for air-conditioning.
If the contract was being renegotiated, the tenant might say "the building signage is 'off the table' " to mean "it's a complete waste of time to bring that up, we'll move before we give in on that" etc.
'dealbreaker' (another answer) might be the thing..
.. but "take it off the table" is the act , and 'off the table' is the state of that thing.