Answer 1: According to all likelihood, it means "when someone wants to turn you into a mean person."
Example: In Star Wars, the bad guys want to get the good guy joining the "dark side of the force," in attempting to arouse anger. In Spiderman III, an obscure and unclear form of alien life turn the good guy into a bad one.
You see the picture.
Answer 2: Oo that means you're in real trouble. GET OUT OF THE SHOWER!