Another way
is to give the victum, er sufferer, a half glass of water and get them to drink it, in 5-7 swallows, while placing your fingers in their ears. The trick is to insert a finger just large enough to fill the entance to the canal so that when they swallow you can feel the changing size of the canal. The snug fit actually restricts some of the movements in the canal and relieves the nerves that are causing the hiccups.
A finger too large doesn't get in deep enough and too small of a finger doesn't restrict the movement enough.