A dangerous drug that's a freebase form of cocaine that can be smoked. Nicknames include rock, work, hard, iron, cavvy, base, or just crack. It's said to be the most addictive form of cocaine there is. It offers a short (but intense high).
Sara: "Did you hear that Rowan tried crack cocaine because his friends were doing it?"
Veronika: "Yeah man, wasn't surprised."