During the 1980s Miller appeared in a famous series of Australian television commercials for Cadbury chocolate, using his stock phrase "Why is it so?", demonstrating a simple scientific principle, and describing how each block of chocolate "embraces substantial nourishment and enjoyment," and contained "a glass and a half of full-cream dairy milk." The ads were sufficiently popular to be played for some years after his death. While in Australia, Miller also appeared in ads for non-stick saucepans and Ampol petroleum which included demonstrations of real principles of physics, albeit briefly.