I came across someone referring to the phrase "何様のつもりか" in the middle of an English-language discussion:
if I were [person X], I would be shouting "何様のつもりか" (although I am not, and so I can't)
Weblio gives a translation of "Who the hell do ... think ... are?"
I guess the translation of phrase makes sense based on its component words (the author is accusing someone of taking over person X's project), but is there any other context I should know about this phrase?