Formal:
* Miłego dnia! (mee-lɛ-go dɲa) - This means "Have a nice day!" and is a polite way to say goodbye.
* Miłego popołudnia! (mee-lɛ-go pɔ-pɔw-ˈdɲa) - This means "Have a nice afternoon!"
* Miłego wieczoru! (mee-lɛ-go ˈvʲɛ-t͡ʂɔ-ru) - This means "Have a nice evening!"
Informal:
* Dobrze się baw! (dɔb-ʒɛ ʃɛ ˈbav) - This means "Have fun!" and is a more casual way to say goodbye.
* Miłej zabawy! (ˈmi-lɛj zaˈba-vɪ) - This means "Enjoy yourself!"
* Super! (ˈsu-pɛr) - This means "Great!" or "Awesome!" and can be used as a response to "Have a good time."
For a specific event:
* Miłego koncertu! (mee-lɛ-go kɔn-ˈtsɛr-tu) - "Enjoy the concert!"
* Miłego meczu! (mee-lɛ-go ˈmɛ-t͡ʂu) - "Enjoy the game!"
The best way to choose the right phrase is to consider the context and your relationship with the person you are speaking to.