This weekend I was stricken with hiccups so persistent they lasted over 36 hours. While the cure ultimately required medical attention, I tried every home remedy I could find online. While nothing could stop them for good, the only supposed cure that actually worked -- if only temporarily -- was apple cider vinegar.
According to the Snopes message board, any kind of vinegar will do:
The most effective singular cure for a bout of hiccups I have seen is when the aforementioned hiccuper had a bad bout in the pub. He was starting to despair when the landlord said he'd pour a shot of something that always cured himself. Expecting a tasty jolt of scotch or something, it was with great surprise that he slammed down a shot of finest malt vinegar. No hiccups.
I tried every method I could find -- some methods so ridiculous they should not ever be mentioned -- and the only one that gave me any respite was the vinegar. It burned on the way down and at first I thought things would be worse, but those 30 minutes gave me enough time to get myself to the doctor and get the problem fixed for good. If you have hiccups that seem like they're going to last forever, you probably shouldn't do what I did and try every method on the internet. But I did so I could report the results. Next time I have the hiccups with an end in sight, I will be reaching for a bottle of vinegar first chance I get.
Foolproof cure for hiccups [Snopes Message Board]