We had an anatomy lecture on the vagus, accessory, and hypoglossal nerves today (CN X, XI, XII). One of the only things that I remember from it is this trick to stop hiccups:
Press down very hard right behind your ears.
Hiccups can be cured by stimulating the vagus nerve, and there is a branch of it that runs behind there. In fact, there’s a whole bunch of information on vagal hiccup remedies. Let me know if this particular one works for you!