French phrase
Ne vous avisez pas de ~ !
Meaning
Don't you dare ___!
When to use it
A forceful prohibition against doing something. It can sound stern or angry and may be used by a superior in formal settings.
Example dialogue
Ne vous avisez pas de parler de ce projet à l'extérieur !
Don't you dare talk about this project outside the organization!
Entendu, je garderai le silence.
Understood, I'll keep quiet.