Informal:
* ਠੀਕ ਹੈ, ਮੌਜ ਕਰੋ (thik hai, moj karo): This is the most common and straightforward way to say it. It literally translates to "okay, have fun."
* ਬਸ, ਮਸਤੀ ਕਰੋ (bas, masti karo): This is another informal way to say it, meaning "just have fun."
Formal:
* ਠੀਕ ਹੈ, ਆਨੰਦ ਮਾਣੋ (thik hai, anand maano): This is a more formal way to say it, meaning "okay, enjoy yourself."
* ਬਸ, ਸੁਖੀ ਰਹੋ (bas, sukhi raho): This is a very polite and respectful way to say it, meaning "just be happy."
You can choose the phrase that best suits your situation and the person you are talking to.