以下是一些表示“玩的开心”的常用短语：
1. Have a great time!
2. Have fun!
3. Enjoy yourself!
4. Have a blast!
5. Play hard and stay up late!
6. Live it up!
7. Make the most of your time!
8. Relax and unwind!
9. Take it easy!
10. Be carefree!
11. Have a ball!
12. Enjoy yourself to the fullest!
13. Savor every moment!
14. Let loose and have fun!
15. Laugh and have fun!
希望这些短语能够帮助您表达“玩的开心”的意思。