gobstopper

A form of the ever-popular jawbreaker. They come in a colorful box and are produced by the Wonka candy company. They are smaller than regular jawbreakers but are smooth and change color as you eat them. The center is, for some strange reason, a softer, pinkish candy.

A gobstopper was the slang term in the British Navy for a large piece of round shot that an officer would make a younger sailor -- say, a teenage midshipman -- hold in his mouth, usually to shut him up.

"Gob" is slang for mouth; related words are gobbet (a lump of food or meat), gobsmacked (surprised, smacked in the mouth), and gobshite. You might tell someone to shut up by saying "stow your gob".