This is going to sound a little weird. But here goes.

I discovered this trick myself. It often works on the first or second try.

The basic mechanics of this trick is to swallow some air, but trap it in the throat, and then swallow on top of that. The second swallow can be done roughly or forcibly to try and shake things up.

Trapping the first swallow of air in the throat, is done in the same manner that you can use to hide something, such as a piece of bubble gum, and then bring it back later. If you are not familiar with this item hiding trick, then you might have trouble getting rid of your hiccups.