We get hiccup's because the brain gets confused what signal to send...

Why do we get hiccups? from MSN

Once in a while, often when you find yourself eating a bit too quickly, your brain sends conflicting signals to your diaphragm and epiglottis: "Close the esophagus and open the trachea--no, wait. I mean, pull the diaphragm and open the--hold it--I mean the food tube--no, the windpipe. Wait. Now, swallow and breathe. Yikes!" Once in a while your diaphragm contracts and forces air through your glottis, and you feel a bump and often hear that "heek" sound. That's when you have the hiccups.

Your nerve fibers have produced too many charged calcium ions near the muscles of your glottis and your diaphragm. They spasm; your brain triggers your nervous system to send a correcting signal, but it's too late or not quite of the right strength, and you hiccup again. Often there's an imbalance that is like a resonance. The signals build up and let go at regular intervals, like a sign flapping in a breeze.

The way to stop the hiccups seems to be to provide a new clear signal to your body--either a signal for swallowing or breathing. That's why for some people, it helps to hold a breath. For others, swallowing several sips of water in succession does the trick. You have to clear or overwhelm the confusing diaphragm-glottal-epiglottal noise. You can do it. Just swallow; I mean, hold your breath. Hiccup--I mean ...