I think the word "just" here means something like "simply".
The shirt is saying something like, "This is a simple situation and you must follow this simple instruction:
do not disturb me.
There are no exceptions to this rule.
Don't ask me why.
Simply do not disturb me."
ell.stackexchange.com/users/2020/Tanner Swett
"Just don't" is often used as a response to the question (or some variation of) "Why not?":
Dad: Don't touch that Kid:
Why not?
Dad: Just don't.
In your example, they're shutting down the question
"Why can't I disturb you?", "What are you doing?",
etc.. before you have the chance to ask it, implying they are expecting you to ask it.
Dad: Don't touch that Kid: - Dad
: Just don't.
It's quite common, so much so that it has made it's way into one-way conversation for comedic effect, hence the t-shirt print.
ell.stackexchange.com/users/118239/George
Just , in this context, is more of an indication that there may be repercussions if you do not heed the previous warning.
It is almost like saying “Don’t disturb me.
Or, else!”
It is almost, but not quite, a veiled threat.
ell.stackexchange.com/users/117795/Dean F.
I vaguely suspect this is a pun of sorts on the Nike slogan "Just do it".
Since in the context of Nike's advertising "just do it" means "do it without even thinking about it", the opposite phrase "just don't" would mean "don't even think about doing it".
ell.stackexchange.com/users/19876/Eike Pierstorff
It means "only" or "simply".
However, the context is important.
Here is a typical case where an imperative sentence is used with "just": Dad: Jimmy, mow the lawn.
Jimmy:
But daaaaaaaaaaad, I don't want to mow the lawn!
Dad:
I'll get ice cream if you mow the lawn.
Jimmy:
But I'm playing a game!
Dad: Mow the lawn now or I'll give you time out!
Jimmy:
No! Please don't!
Dad: Stop complaining and just mow the lawn!
In this argument, it means: The only thing you should do is mow the lawn.
You should not complain, or argue, or do anything else.
Obviously, it also conveys anger or frustration.
Compare with a more common use of "just": Do you want ketchup or mayo or garlic yoghurt?
Just ketchup, thanks.
Here it means: The only thing I want is ketchup.
I do not want mayo, or garlic yoghurt, or anything else.
In the argument context, it can also be seen as "simply". "
Simply mow the lawn, without extra complications like complaining or arguing."
The shirt is similar to the argument, except much shorter, and perhaps with less anger and more frustration.
Dad: Don't open the door.
Jimmy:
But daaaad, I want to play outside!
Dad
: Just don't open it!
Mad scientist: Don't press the button.
Jimmy:
But it's shiny and red!
I want to press it!
Mad scientist: Just don't press it!
In this case, nobody is complaining about being told "do not disturb" - obviously, since it's a T-shirt and not a two-way conversation.
The writer is acting as if someone did, anyway.
It's like a pre-emptive answer, because the writer is feeling especially frustrated and is expecting someone to complain: Mom: Don't eat the cookies.
Just don't!
Jimmy:
But - Mom
: I said, "just don't!"
Last time you ate all the cookies and we had to cancel the family picnic!
ell.stackexchange.com/users/26915/user253751
Like @tanner-swett's answer, I believe "just" should be interpreted to mean "simply".
But here's a bit more of an unpack: "Do not disturb.
Just don't.
"
I want you to refrain from disturbing me.
I want this very very much.
No matter what the situation may be, no matter who is in peril or what has happened, do not disturb me.
You do not need to think about anything else.
The order is simple.
It is three words.
You do not need to make it more complicated than that by trying to think of an exception.
Simply this: do not disturb.
ell.stackexchange.com/users/10015/Ross Presser
Without Further Explanation
Aside from the other answers suggesting "Simply" and "Only" as possible synonyms.
In this sort of context, the word Just is being used to emphasise that there will be no justification or explanation.
An authority figure saying "Just do it" is allowing no argument.
In the context of the T-shirt, they're saying not to bother them, and that they don't want to explain what will happen if you do.
In sentences like this, the phrase is usually fully functional without the word "
Just"It's similar to spelling out the word "Period" on the end of a sentence to emphasise it and indicate that there's nothing more to say.
"I will not stand for this nonsense!
you're wrong.
Period!"
"Do not Disturb.
Don't" It short-circuits the following question
, someone asking why they shouldn't disturb you, by preemptively answering it.
ell.stackexchange.com/users/74520/Ruadhan2300
"Just" here has the meaning "only".
As the previous statement was an order it is saying that that the requirement is to obey the order without doing anything else (like discussion, delay, etc).
ell.stackexchange.com/users/116305/Peter
It can simply mean no reasons for not disturbing will be given, and you are expected to take the imperative utterance to be sufficient with no further justification.
ell.stackexchange.com/users/46779/Michael Hardy
It was written on a T-shirt: "Do not disturb. Just don't." What does "just" mean here? Does it mean that all I want is that you don't disturb?  There is a difference of opinion between the respondents. What is the opinion of someone whose mother tongue is English?
What does the word "just" mean in this context?
ell.stackexchange.com
<meaning><meaning-in-context><colloquial-language><imperative-sentences>
ell.stackexchange.com/questions/253741
ell.stackexchange.com/users/118194/mbmoosavi
Here, the word "just" means something like "simply".  There are no exceptions to this rule. It means "only" or even "simply"
It means "only" or even "simply"