A maniacal character, maybe the narrator, is basically being given an opportunity to use his "evil" skills, so to speak. This may mean that he's only having thoughts of taking out his anger on someone, or that he's been asked to do so on behalf of another person (like a hitman would). Lines like "I'll kill it if you want me to" and "I'll trade you blood for dirty cash" support this thought. The character even enjoys this type of crazy behavior, and feels "at home." And once the dirty deed is done, he says, the targeted person will be "out of sight, out of mind."