what causes the hiccup
Even a sudden change in temperature can trigger a bout of hiccups. Overeating or reflux are the most common causes [of hiccups], and the internet is full of other potential causes. Changes to your the brain can also cause hiccups, and some drugs that act on the brain can cause them. Also, brain trauma (such as stroke) can cause severe hiccups.
1 Hiccups are the result of an involuntary spasm of your diaphragm, which causes the space between your vocal cords to close, leading to the characteristic âhicâ sound.  Overeating, acid reflux, drinking alcohol or carbonated beverages, or emotional stress can trigger hiccups.