Aerophagia
Aerophagia is a medical term [3] that describes the continuous and repetitive swallowing of air and it is the major reason hiccups occur. Perhaps due to old habits, a lot of people tend to take in air through their mouths when they are excited, upset, or shocked. Chewing gum or eating candy can contribute to persistent hiccups too when you experience aerophagia. So if you constantly have hiccups, you might want to check your habits and maybe stay away from gum too.