Jazz Chalk, a synonym for cocaine, particularly when used by musicians in Maryland. A subtle reference to the term jazz cigarette, the term isn't necessarily creepy but can be used to imply an odd circumstance under which cocaine is used.
After we finish these crabs let's go write with some jazz chalk before the show.
I took her to school last night, teacher brought out the jazz chalk.
Refers to the chalkline drawn around a corpse in movies. The 'line' idea is mostly fictional, since it contaminates the crime scene investigation, but it serves as more dramatic metaphor for murder.
You better watch how you're talking and where you're walking, or you and your homies might lined in chalk. (Coolio - Gangsta's Paradise)