While I generally prefer Vietnamese coffee or maybe some chai, coffin varnish style coffee can be a powerful tonic for when you're facing a major deadline and know that you won't be sleeping this week. You know you've done it right when a fine iridescent sheen forms on the rim of the cup, a oil slick in miniature. If you squint, you can see the seals dying. It will have a strong chemical aftertaste, sometimes with an almost yeasty undertone. It will blend with the pool of acid in your stomach with quite profound results; it's not the caffeine keeping you awake, it's the pain in your stomach and the awful taste in your mouth.
The wonderful world of coffin varnish is not limited to bean-derived beverages, but the characteristics and effects of coffin varnish are largely the same regardless of the actual contents. A personal favorite of mine is what, in an earlier era, might be termed rotgut.
Unlike the coffee form, which is best made at home (Starbucks having not yet caught on to this particular market segment), the alcoholic form is usually best consumed in the appropriate atmosphere. Go to your favorite run down dive, and ask the run down bartender for a double of whiskey. When they ask what kind of whiskey, the response is simple: "Cheap".
If you've gauged your dive correctly, he or she will then reach under the counter and pull out a bottle. It will probably contain a brownish liquid of some sort, and odds are high the brand name will have either Kentucky or Tennessee in it. After performing the appropriate exchange of goods and services with bills, don't just gulp it down. Contemplate it. But don't smell it; it doesn't smell good, and if anything the smell will make you toss it and order something decent. Presumably if you've gone this far, you've got a solid reason for wanting to fuck yourself up. Think about that reason, think hard, and try to work yourself into either a suicidal depression or homicidal rage. It's surprisingly easy to do, and will help get your body ready for the upcoming shock. Now take a solid hit. You'll probably want to vomit at this point. Smoking a cigarette or ten will help kill the taste and calm your raging system. Order another. Repeat until last call. Stumble home, or for bonus points, pass out in an alley, or in front of your ex's house.
To echo xunker: "If it doesn't kill you, at least you'll go blind and loose all fine motor skills."