Heh, and I came to say what eanjay said: drink water upside down!

Stand up, hold a glass of water out in front of you at about waist level, then bend at the waist so that your lips will be at the rim of the glass on the side that's away from your legs. Tilt the glass slightly, away from your legs, so that you can drink from that far-side rim, You will have to hold your breath to do this without sputtering. Take two or three gulps, or even more if you can. Then you can straighten up. If the hiccups persist, repeat (you'll be bending lower this time to get to the water).

Something about the combination of holding breath, swallowing and the angle at which it's all being done (and maybe the diaphragm contraction from bending over?)... works for me every single time.