There are several alternative ways to say "have fun" or "have a great time" at a concert. These expressions can help you convey your excitement and well wishes to someone attending a concert. Here are some options:

1. Enjoy the show! [1]
2. Rock on! [1]
3. Have a blast! [1]
4. Dance the night away! [1]
5. Make memories! [1]
6. Have an amazing time! [1]
7. Let loose and have a great time! [1]
8. Sing your heart out! [1]
9. Get lost in the music! [1]
10. Have a concert experience to remember! [1]
11. Party like there's no tomorrow! [1]
12. Have a fantastic time at the concert! [1]
13. Soak up the energy and enjoy every moment! [1]
14. Have a rocking good time! [1]
15. May the music lift your spirits and bring you joy! [1]

Learn more:

1. What are other ways to say 'have fun/have a great time ...
2. expressions - How to say "I hope you will have fun/it will be great" in a different way? - English Language & Usage Stack Exchange
3. 20 Simple Responses to "I'm Glad You Had Fun"