knock yourself out
US /nɑk jərˈsɛlf aʊt/
UK /nɑk jərˈsɛlf aʊt/

1.
silakan, buatlah sesuka hati
used to tell someone that they can do something if they want to, even if you think it is not a good idea or will not be successful
:
•
You want to try to fix the car yourself? Sure, knock yourself out!
Awak nak cuba baiki kereta sendiri? Tentu, silakan!
•
If you think you can finish all that work by yourself, knock yourself out.
Jika anda fikir anda boleh selesaikan semua kerja itu sendiri, silakan.