Waluigi

— Luigi plays by the rules; Waluigi cheats and causes chaos. An AI was designed to find drugs for curing human diseases; an inverted version, its Waluigi, suggested molecules for over 40,000 chemical weapons. All the researchers had to do, as lead author Fabio Urbina explained in an interview, was give a high reward score to toxicity instead of penalizing it. They wanted to teach AI to avoid toxic drugs, but in doing so, implicitly taught the AI how to create them.