The Bubble Bomb is a bomb created by Cassidy which was designed to completely eliminate all Bubble People from Comic World. While the bomb ultimately did not destroy all the Bubble People in Comic World, it did destroy all the Bubblians from Bubbletopia when it went off.
The bubble bomb is a green rectangular-shaped bomb. It is surrounded by yellow circular grooves. It also has a timer right in the middle which tells the user when it will go off.
The Bubble Bomb was used by Cassidy when she gave it to Bob to hide in his basement. Later, Bob unintentially caused the bomb to go to Bubbletopia and destroy all the Bubblians.
The Bomb was designed to have a 10,000 kilometer blast radius, well over the amount needed to cover all of Comic World. In order to achieve the desired effect of destroying Bubble People, there are too main functions of the Bomb.
The first function is that the Bomb sends out pulses that react with certain molecules, causing them to combust. These molecules are found in Bubble People but not in Stick People. The second function of the Bomb was that it could send pulses which react with soap and create a reaction strong enough to pop whatever contained it. Cassidy's poor mental state at the time may have been the reason for the second function, since Bubble People aren't actually made of soap.
The Bomb also contains a delay function and a countdown clock so the bomb could be set off at a later time. Cassidy's poor mental state was probably also a factor in this idea because there is no clear reason why she would need to set off the bomb with a delay rather than just initiate it as soon as she made it.