Okay, this is a little challenging to describe, it is something that I've always been able to do. I've tried to describe it to many people, but so far only ~3 people have successfully executed the technique.
First, practice a "false hiccup". Do this by mildly inhaling, then abruptly close off the inhalation somewhere in the throat. There should be some kind of "vacuum" effect that feels similar to a hiccup, you should feel this somewhere between your belly and chest.
Next, time this "false hiccup" precisely with a "true hiccup". If done correctly, the hiccup should "cancel". Using this technique, it has been many many years since I've hiccuped more than twice in a row.
