This is said when you meet somebody you don't know under unpleasant circumstances and you want to show extreme displeasure. <Ring ring!> "It's 6 o'clock in the morning. Who the hell ARE you!?" "Sir, we're taking a survey on the buying habits of people in your age group...." "Get STUFFED!" <Slams phone down> It is also used to express the questioning of a person's position or authority. "I think you should stop eating so many donuts - they'll make you fat." "Who the hell are YOU to tell me what to eat!?" [Translation - Who do you think you are that you can give me orders on what I can eat. You have no right to do that!]

It means"你他妈的是谁“，"hell" is modal particle in this sentence

It means"你他妈的是谁“，"hell" is modal particle in this sentence

= Who are you?