1. An exclamation used to emphasize surprise, shock, anger, disgust, etc. In this phrase, "the hell" is used as an intensifier. What the hell are you doing? You can't come in here! What the hell? I just had this fixed, and now there's a dent in it! Just what the hell is going on here?

2. Why not; one might as well; it makes no difference anyway. A: "Do you think we can add some extra effects to this scene?" B: "Sure, what the hell." Let's see, I'll take a gallon of milk, a carton of eggs, a loaf of bread, and… what the hell, one of those bouquets of flowers, too.