Why do we get hiccups?

Let's start with what a hiccup is. A hiccup is a short, sudden burst of inhalation. Breathing is controlled by the diaphragm. It's a large, dome-shaped muscle that separates the chest from the abdomen. When it contracts, it moves down. This increases the overall size of the chest which causes a decrease in internal pressure. Air will rush into the lungs in order to equalize that pressure difference. When the diaphragm relaxes, it moves up. This decreases the volume and increases the pressure, and air rushes out. A hiccup occurs when the diaphragm spasms and forces you to suddenly suck air into your throat. This causes your vocal cords to suddenly close creating the standard "hic" sound.
There's no one reason why hiccups occur. Truthfully, this is still more of a mystery than anything else, and studies are still being conducted to figure out why we hiccup. With that said, research shows that hiccups can happen for a variety of reasons. Some of those reasons are physical while other reasons are emotional. The reason that those can trigger weird, irritated diaphragm movement is because the actual irritation is occurring in the nerve that connects the brain to the diaphragm. I'll list some common hiccup triggers.
stress
sudden changes in temperature
feeling nervous
feeling excited
eating or drinking too much too quickly
drinking too much alcohol or carbonated beverages
https://kidshealth.org/en/kids/hiccup.html

https://www.iflscience.com/health-and-medicine/why-do-we-hiccup/

https://www.medicalnewstoday.com/articles/7623.php