What is a hiccup?
Answer:
It is a spasm of the diaphragm. Science doesn't really have a correct explanation of why it happens. Basically, when the diaphragm contracts, it pulls downward, decrease the pressure in the rib coop, and thus pulls in nouns (because of the negative pressure). When the spasm happen, the diaphragm pulls down sharply, causing a sharp inspiration of breath.
A spasm surrounded by the diaphram