From one of the more vivid sections of David Carr's incredible memoir Night Of The Gun, here's a description of what it feels like to smoke crack:

It is, for want of a better metaphor, akin to scoring the winning touchdown in the final game of a championship season, and then reliving that moment of crossing the goal line over and over until the rush ebbs. And rather than the gradual rile up from powdered cocaine, crack makes it happen immediately and profoundly. Senses are more acute, pupils dilate, blood pressure and body temperture rise, and you feel like the lord of all you survey, even if it is a crappy couch and a nonworking television in a dope house.

And then it goes away. There is only one thing that appeals after a hit of crack, and it is not a brisk walk around the block to clear one's head. There is no such thing as a social crack user. Many normal people get a sense of its lurid ambush and walk away. Others take another hit. In this chronic scenario, the brain argues against the dopamine festival by becoming far less receptive. Higher doeses lead to diminishing returns and a brutal cratering after ingestion. What seemed like a way to leave the gravitational pull of this ball of dirt becomes a shovel repetitively deployed to dig a hole that the user can not crawl out of.

I have not smoked coke in two decades, but I remember its every aspect. A pre-high emerged even as the drug was being made. The heart would begin to race and the pupils would flare in anticipation...