The candy cannon appears in some levels.
How does it work?
See that little window with a candy inside? Every time you clear the space in front of the cannon, that candy will appear.
You will often see special candies inside the candy cannon that can help you clear your level.
The upside down candy cannon
Sometimes, the candy cannon is shown upside down. This one requires two things to dispense a candy. First you will have to clear the space above the candy cannon but most of all you will have to make sure that there is soda above the candy cannon for the candy to go up!