That’s how memory works. One experience (the end of ballet class) causes certain neurons to fire, and those neurons can get wired to neurons from another experience (getting bubble gum). Then each time we undergo the first experience, our brain connects it with the second one. Thus, when ballet ends, our brain triggers an expectation of getting gum. The trigger might be an internal event—a thought or a feeling—or an external event that the brain associates with something from your past.
