Shaggy & Scooby-Doo Get a Clue! - Season 2 Episode 10 Don't Get a Big Head
Overview: Dr. Phibes, tired of being outsmarted by our heroes, revises his nano formula to increase his IQ. It also inflates his head. Now, Shaggy and Scooby must stop him from releasing a gas that will drastically lower the world's intelligence.