How do you say slumber party in French?

There isn't a direct translation for "slumber party" in French. However, you can use a few different phrases depending on the context:

Formal:

* Soirée pyjama: This is the most common and literal translation.

* Soirée de nuit: This means "night party" and can be used for a sleepover.

Informal:

* Pyjama party: This is a very common and informal way to say "slumber party" in French.

* Soirée entre filles/garçons: This means "girls'/boys' night out" and can be used for a slumber party.

Ultimately, the best way to say "slumber party" in French depends on the specific situation and the level of formality you want to use.