During a hiccup, your diaphragm spasms causing you to take a quick breath in. This breath in is then interrupted by the epiglottis closing and causing a “hic” sound. (FYI, the epiglottis is a flap that covers the space between the vocal cords).
It is possible to stop them within 60 seconds or so by swallowing a teaspoon filled with dry sugar. Specialists believe the abrupt sweetness on the tongue overloads the nerve endings in the mouth and blocks the hiccup spasm.
A study published in the New England Journal of Medicine and also found on Medicine.net showed when a spoonful of granulated sugar is eaten, it was found to be effective in 19 out of 20 patients.