The word "坏蛋" is formed through a vivid metaphorical combination. It literally translates to "bad egg", drawing on the universal image of an egg that is rotten or spoiled at its core. This concrete, physical idea of internal corruption is then applied figuratively to a person, branding them as someone who is fundamentally rotten or villainous in character. The term’s effectiveness and memorability come from this simple, visceral analogy, making the abstract concept of badness immediately understandable through everyday imagery.