Well said, it is caused "sometimes" by drinking carbonated beverages or alcohol, irriration of the phrenic and vagus nerves and sometimes by some metabolic disorders. Hiccups goes away even without any intervention but others do the following; Drink water, having someone to fright you or inflict shock and holding one's breath which in terms trying to regulate the contractions.
And Pat, yes it is possible to get air inside your stomach, which is very uncomfortable. If you try percuss your abdominal area which is "not" only your stomach, you will either hear a dull or flat sound or tympany but dull or flat usually indicates a solid organ like our liver. If you percuss it and the sound is resonant that indicates the presence of air in the structure.
