source
C'est pas Versailles ici! *
* It's not Versailles in here
Expression used often by Parents and grandparents
Typically used by parents when their children leave a room but forget to turn off the light or if they use electricity in a wasteful way. Reference to the Palace of Versailles.
"Éteins la lumière quand tu sors de ta chambre, c'est pas Versailles ici!"
"Turn off the lights when go out of your room, we're not in Versailles here!"
9 out of 10 French speakers have heard this