"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.

Of course, it's on a T-Shirt, so is most likely for comedic effect, but I think the point still carries.

"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.

"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.

Dad: Don't touch that

Kid: -

Dad: Just don't.

Of course, it's on a T-Shirt, so is most likely for comedic effect, but I think the point still carries.

"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.

Of course, it's on a T-Shirt, so is most likely for comedic effect, but I think the point still carries.