Stimulate you phrenic nerve by vigorously rubbing the roof of your mouth, just behind the ridges that you feel behind your teeth.
My brother was a quadrepeligic, and couldn’t breathe on his own. he was the first person to have a phrenic Nerve pacemaker surgically installed. Before they did the surgery, they tested him to see if he would be a good candidate. They put electrodes on his phrenic nerve and he hiccupped, showing them that the nerve was still intact enough for the pacer to help him breathe. Somewhere I heard about stimulating this nerve 9wheich ends in the roof of your mouth) to cure hiccups. it made sense to me because of what happened with my brohter, so I tried it. it has worked every time!! You can read more about this here