I first posted this in 2005, and still get a thank-you e-mail or two every month from someone who could not stop their hiccups. So, as a public service, here it is again -- my Guaranteed Hiccup Remedy:
Tilt your head back just enough that your neck is stretched a little bit. Inhale and hold a deep breath. Take 7-8 sips of water or a similar non-carbonated beverage. Exhale and discover your hiccups gone.I don't know the science behind this, but you're welcome.