I found this very effective information from Cognitial, I just thought others might want to know so I post it here.  For overall best results, please try to do the steps as quickly as you can and try very hard not to let any air out. Here are the steps:

Step 1: Start by inhaling through your mouth until your lungs feel full (when it feels like you cannot inhale any more.... your lungs will basically stop taking in air).

Step 2: Swallow. You are not really swallowing anything but it seems that without this act, it doesn’t work. Do not let any air out.

Step 3: Now inhale some more until your lungs feel full again. You may not be able to inhale a lot, but do get some more air in. It will start to get difficult to do this as you go, but keep trying. You obviously can’t suck in as much air as you did initially, but just a little will do (think of it as taking a “sip” of air but directly into your lungs).

Step 4: Swallow again. This too will start to get difficult as you go. Do not let any air out.

Step 5: Repeat steps 3 and 4 (inhale and swallow) until you cannot swallow again. While it seems you can almost always suck in just a little more air, it is actually the swallowing that gets to be impossible. When you feel like you cannot swallow again, swallow again anyway. It will be hard to do, your face will probably turn red, and you may make squeaking sounds. But you CAN swallow one last time. By this time, your lungs should also be quite full and it should be difficult to get much more air in as well. While you should try not to let any air out, if you have really repeated steps 3 and 4 as many times as you can, you probably will end up letting a little air out before you can take that last swallow. If you find that air keeps escaping out of your nose even early in the process, try squeezing it shut with your fingers.

Step 6: Exhale.

If done correctly, the whole process should take around 30 seconds, and your hiccups will be gone. This has never failed me, and from the testimonials below, it seems to work for many people. I believe that for those that it does not work for, they are not repeating steps 3 and 4 as many times as they can. When you think you cannot possibly swallow again, try to do it anyway; same goes for inhaling. It also seems that not letting any air out during the process is important. If you hiccup while trying to do this, try not to exhale after the hiccup (the hiccup will force more air IN, working with you). If you do let air out, it is best to start over from step 1. It has also been reported by one visitor of this site that it seemed to work better standing (particularly as opposed to laying down), but I have done it successfully both standing and sitting down. Your experience may vary.

I have been doing this many years, and it always works for me. This is similar to another cure I have heard, which is to hold your breath. That alone has never worked for me. Somehow I got the idea to add swallowing to it, and the result was success. An interesting side-effect is that (for me at least) for around 15 or 20 seconds after doing this, you feel like you want to hiccup, but it never happens. I am not sure if this is because you expect to hiccup again or what, but the nice thing is the hiccups do not return.

If you have tried this and it does not work, I suggest repeating steps 3 and 4 at least one more time than you were able to originally. And of course, while it does seem to work for almost everyone I have told, it is possible that it will not work for everybody. Although I personally feel that the problem is not the method, but rather the execution of it; of course I am a bit biased. :)

If you have tried this and it DID work for you, great! I would love to hear about it too, so submit a testimonial and let me know. I will add it to the testimonials below just as soon as I can.

Many thanks to Cognitial for posting "30-Second Hiccup Cure", It was very helpful to me and my friends.