One good remedy is to take a deep breath. Study the hiccup first of all and see what its rhythm is. If you find the hiccup comes once in seven seconds, that is, you hiccup and then wait a few seconds, that is the rhythm. If it comes once in twenty seconds, that is the rhythm.
When you find what the rhythm is, notice when you hiccup and then wait a few seconds until it is about three or four seconds before time for you to hiccup again.
Then take a very deep breath — as deep as you possibly can. Then take in just a little more and hold the breath. Look at your watch until the period has gone by five seconds and you have interrupted the paroxysm; you have broken up the rhythm, and if you do that two or three times it will, in the great majority of cases, stop the hiccup entirely.
Another good thing is to drink a little hot water.
Image: World War I nursing recruitment poster (c1917)