In Italian, one forms the negative imperative in the second person singular by using the particle "non" with the infinitive: non fare, non parlare etc.
This always baffled me, because the use of the infinitive as imperative is a thing in Russian as well, but it's extremely rude, and it's very niche: military commands, dog commands, impersonal language in safety signs and so on. I realize that it doesn't work like this in Italian, but I just can't help feeing a little bit uneasy every time I use it.
To my knowledge, Italian (with its regional varieties) is the only Romance language where the infinitive is used as an imperative.
What is the origin of this pattern?
My guess it came from Latin noli + imperative (like in noli me tangere), which, as far as I understand, literally means "you don't want to touch me" and as such is actually a more polite form. But I couldn't find anything to confirm or disprove this theory.