How do you say have lots of fun in french?

There are a few ways to say "have lots of fun" in French, depending on the context and level of formality:

Formal:

* Amusez-vous bien! (This is the most common and polite way to say it.)

Informal:

* Amusez-vous! (Shorter and more casual.)

* Faites la fête! (Literally "Party!" - implies a more lively, social kind of fun.)

* Profitez bien! (Means "Enjoy yourself!" - implies a more relaxing, personal kind of fun.)

Informal, playful:

* Éclatez-vous! (Literally "Explode yourselves!" - implies a really good time.)

* Faites-vous plaisir! (Means "Do yourself a favor!" - implies indulging in something enjoyable.)

The best choice depends on who you're talking to and the situation.