Here’s a bizarre cure: Pour yourself a glass of water, put a paper towel on top, and sip the water through the towel! That forces your diaphragm to work harder to get the water down. It also changes your breathing pattern, which counteracts the irregular movement of your diaphragm while you are hiccuping. After a few sips, your hiccups should be gone.
I haven’t tried this yet, so if it works for you, please let me know.