From No Game No life (Anime)
Context: this gamer guy is pretty pissed that his sister is falling asleep and afraid that he's gonna die in the game, but then she falls asleep, and gets hyped/irritated and says:
From what I can gather, じゃねえか is a colloquial form of じゃないか, but what is やったろう and how come it can attach じゃねえか if it's not a noun (or is it?).
Edit: I read the suggestions, and while the "didn't you?" meaning じゃないか makes sense, I still don't know what やったろう is supposed to mean. Based on the context of the situation, I think the meaning should be something like "you did, didn't you?!" because it's his reaction to his sister's having fallen asleep a second ago. Interestingly enough, the official translation of the sentence is "Fine, bring it on!".
Edit2: Found the solution to the meaning of the expression in the comments, but I would still like to hear a comprehensive explanation. Why does it mean what it means, i.e willingness to take on a difficult situation?