Place half of a teaspoon of dry sugar on the back of your tongue.
Do this 3 times, 2 minutes apart.
In a 1971 study, granulated sugar as treatment for hiccups in conscious patients, by Engleman, Lankton and Lankton, they found that eating a spoonful of granulated sugar was effective in curing hiccups in 19 out of 20 patients.
It works due to vagus nerve stimulation, as do most remedies that do not interfere with breathing. Ultimately that stimulation is a distraction that causes your brain to forget about hiccuping. So it is not that sugar is a magical ingredient, but rather that it is one of many substances that can stimulate that nerve and cause a distraction.
Granulated or dry sugar is simply sugar that comes in a bag or out of a shaker. It is any sugar with the molasses removed and nothing added (like liquid).