The hiccup reflex is an involuntary action that occurs when the diaphragm, a muscle that helps with breathing, suddenly contracts. This contraction is followed by a quick closure of the vocal cords, which produces the characteristic "hic" sound. Hiccups can happen for various reasons, including eating too quickly, consuming carbonated beverages, or experiencing sudden changes in temperature. Most hiccups are harmless and resolve on their own within a few minutes. However, persistent hiccups lasting more than 48 hours may indicate an underlying medical condition and should be evaluated by a healthcare professional.