a hiccup (also spelled hiccough) is sudden tightening of the diaphragm, which is a muscle inside the chest and below the lungs that causes air to be pulled in. a short time after diaphragm contracts, the throat suddenly closes. this closing stops the air from flowing in, and results in the "hic" sound that gives "hiccups" its name. a hiccup is a reflex, a kind of action happens in the body without trying. hiccups often repeat several times per minute, and end on their own after a few minutes.