In the real world, bubblegum is a delicious candy, fully enjoyed by chewing until the sugary sweet flavor has diminished to nothing. Then, said candy is to be either spit out into an appropriate receptacle for trash and the like, or stuck under a chair, desk, table, or other object that has an underside. Usually comes in a pack. Can come in many varieties of flavor, texture, and sugar content. Can also be used to help one quit smoking (a nasty habit) or to whiten one's teeth. The "bubble" prefix is intended to imply that bubbles can be blown from the gum after it has been chewed for an adequate amount of time, most likely used to entice children into chewing bubblegum, giving them yet another way to annoy those around them.
Juicy Fruit, Dentyne, Bazooka, and Trident are all types of bubblegum.