Hiccups are caused due to the involuntary contraction of diaphragm. Diaphragm is a partition that separates chest and the abdomen. It is the muscle located just below the lungs. It is caused when diaphragm becomes irritated. It is needed when we inhale air and it goes from our nose to our mouth and then from the wind pipe to your lungs. When we inhale air very quickly, air suddenly gush in and causes hiccups. When air hits your voice box, then it produces a strange sound which is called hiccup. The reasons for hiccups can be eating quickly, laughing out loud and having spicy food. If you have undergone any abdominal surgery, then also sometimes it can irritate the nerves of the diaphragm and hiccups cause. One of the biggest reasons for hiccups is consumption of alcohol. Most of the hiccups are harmless and mild and they go on their own but if you get hiccups for more than 24 hours, then you must consult a doctor.