Vocabulary
네가 네 자신을 뭐라고 생각하다
who do you think you are?
Meaning
네가 네 자신을 뭐라고 생각하다 — who do you think you are?
Why this form?
네가 뭔데? — who do you think you are? / who are you to…? : directly challenges someone’s authority or standing; 네가 네 자신을 뭐라고 생각해?! explicitly questions how that person sees themselves.
Forms not to confuse
네가 뭔데?
네가 뭔데 나한테 명령해? — Who are you to give me orders?
Examples
네가 네 자신을 뭐라고 생각해?! — Who do you think you are?!
넌 네가 누구라고 생각해? — Who do you think you are?