Holding my breath generally works, but only if I do it like this:

• breathe in and out as normally as you can
• take a big breath in, big big. Fill your lungs alllllll the way up
• hold for as long as you can
• do not exhale suddenly!
• when you cannot hold any long, let the air out slowly, shape your mouth as if you’re whistling to do so. Like an small o shape.
• nice and slow until you’ve exhaled completely.
• repeat if required, but make sure you take normal breaths as per step one so you don’t hyperventilate

This helps me, as generally hiccups are caused by the diaphragm spasming. The full-lung breath-hold helps to like, reset it. And the very slow exhale is to stop the diaphragm from starting again from the shock of a sudden big exhale.

Hiccups happen when your diaphragm gets out of sync with your breathing. Most of the effective methods force these to re-synchronise. Drinking water out of the BACK of the glass makes you bend over forwards, which temporarily halts your breathing and when you straighten up to swallow, you start breathing again in sync. Usually. Also you might like to slow down the rate of eating, as gulping air along with food can set off hiccups. As a survivor of a boarding school where food happened in a lions on the kill fashion, I learned to bolt food as fast as possible. This caused quite a few issues that I had to learn how to slow down eating to fix. Hiccups was only part of it.

Hold breath and try to burp. That works for me.