While a doctor might claim that all hiccup "cures" are really just old wives' tales that have zero effect, other people claim that their favourite pet cure works every time. Interestingly, some of these folk remedies are on the correct path by having at least some basis in the science of breathing. What method you choose (and boy, are there plenty) is up to you, but if it doesn't work, by golly, one of them should. Here's a roughly definitive list to get you started.

Breathe in as much as you can.

Without letting any air out, swallow. If you can breathe in a bit more, do so. Keep swallowing and inhaling until you can't swallow or inhale any longer.

When you absolutely can't swallow anymore, exhale all the way in a controlled fashion. Your breath should be reset.

Try the open-mouthed swallowing method. 

Open your mouth and keep it open for a couple of minutes. If you feel the need to swallow, do so, but try to keep your lips apart when you do.

Keep gulping every few seconds, especially when you feel a hiccup might be coming. A couple of hiccups might escape, but with continuous gulping, hiccups should be gone within 3 minutes.

Make sure you are not wearing anything tight around your chest. If you are, loosen it.

Imagine breathing in a figure eight. 

As the out-breath reaches the end, slow the breath and twist it around so that it becomes the in-breath. Then simply create a figure eight of continuous breath.

The hiccups will subside almost immediately. It usually works within 10 cycles.

Another way to visualize this is to inhale as much as you can hold, then exhale all but a small amount of air. Continue doing this for 15-20 seconds, or until the hiccups have gone.

Try to stretch your diaphragm. 

Slowly breathe in until you feel like you can't inhale any more, trying to get a feel for extending the breath down towards your abdomen. You are trying to stretch your diaphragm to interrupt the hiccups.

Hold your breath for 30 seconds. Exhale slowly until your lungs are empty. Repeat 4 to 5 times or until you feel better.

Use your tongue and ears. 

Inhale and exhale once slowly. As you exhale, push as much air out as possible (until your body forces you to inhale again). Then, inhale deeply and stick out your tongue. Hold your breath and your nose for 40 seconds with your fingers in your ears.

Exhale slowly. If you feel as if it is not going to work, try again. After all, 3 times is the charm.

Simulate breathing. 

Take a deep breath and hold it. While doing so, plug your nose and close your mouth. Now begin to move your diaphragm as if you were breathing in and out rapidly.

Exhale once the hiccups disappear or you need more air. Repeat if hiccups persist.