Normally, when you breathe in, the muscles in between your ribs contract, pulling your ribs outward and expanding your lungs. At the same time, your diaphragm (which divides your chest from your abdomen) moves downward, creating space in your lungs and causing you to suck in air. When you get the hiccups, these things happen uncontrollably and much faster than when you’re taking a normal breath. Meanwhile, the space between your vocal cords suddenly snaps shut, blocking the airflow. Hic!