It's a black/brown liquid substance, usually served hot in something called a "coffee mug" or cup. It comes in more flavors than some desserts I know of, but it all comes down to two basic flavors, really: leaded or unleaded, regular or decaf.

If you've never had a cup o' joe, then you're in for a big surprise- it's addictive. Woefully so. Cigarettes at least get to taste horrible most of the time, but coffee can be as sweet as ambrosia and twice as effective. One cup can perk you up, but just as with any drug, you can build up a tolerance to it. If you're addicted, by then, just give up to it and try to use some self-control. Three cups, for me, can leave me with the shakes and a queasy stomach for hours. That said, I still glut myself on it whenever I go to Café Coco. Thank God I don't keep any in the house or own a coffee maker!

A cup o' joe, really, though, is a sign of fashion and style more than anything else. You could say "cup of coffee", but that has the same sort of interest and appeal as calling someone a "penis" when you really wanna call 'em a "prick."