Pop Rocks
Pop Rocks are a kind of candy with carbonation added to make a "popping" feeling in the mouth of the person eating them.
Other websites
Images of US patent 4289794 for Pop Rocks from the U.S. Patent and Trademark Office
Pop Rocks: The Inside Story of America's Revolutionary Candy, book detailing the story of Pop Rocks development to Pop Rocks today
How do Pop Rocks candy work?, an article from HowStuffWorks that explains how pop rocks candy is manufactured and also has links to the original patent
Candy