Here's a tip if you would like to quit but can't because the withdrawal is awful.

Wait until you get food poisoning or the flu. You'll probably take some time off work and you'll probably (and should) be under the care of a doctor. You might as well throw in the awfulness that is withdrawal and get it over with.

I turned the hell of "how old was that yogurt I just ate?" into an opportunity to quit my 6 cup a day habit. I'm a little nuts in that I kept some coffee by my bedside and every time I was about to yarf I took a gulp...

I haven't had coffee since, but I did have to be careful not to replace it with some other caffeine source.