Formal:
* Amusez-vous bien: This is the most formal way to say "have fun" and is used when addressing someone you don't know well or in a formal setting.
Informal:
* S'amuser: This is a more informal way to say "have fun" and is used with friends or family.
* Bien s'amuser: This is similar to "s'amuser" but emphasizes the idea of having a good time.
* Profiter: This means "enjoy" and can be used to say "have fun" in situations where you want to emphasize the enjoyment of the activity.
Slang:
* Bonne ambiance: This literally means "good atmosphere" and is used to wish someone a good time in a relaxed setting.
* Bon plan: This means "good plan" and is used to wish someone a good time if they are going to do something fun or interesting.
Here are some examples of how to use these phrases:
* "Amusez-vous bien à votre soirée!" (Have fun at your party!)
* "S'amuser bien à la plage!" (Have fun at the beach!)
* "Profitez bien de vos vacances!" (Enjoy your vacation!)
* "Bonne ambiance à la fête!" (Have a good time at the party!)
* "Bon plan pour le week-end!" (Have a good weekend!)
The best way to choose the right phrase is to consider your audience and the context.