Bomb-ass weed from some mysterious country (perhaps jamaica?) that will knock you flat on your ass. It's said that only the biggest pot-heads are worthy to smoke it, and only the richest mutha-fuckas can afford it.
Charlie- Hey Coker, what weed you sellin'?
Coker- I got that purple dank.
Charlie- Damn son! You 'bout to make a dime! Can you cut a brother a deal?
Coker- Fuck you! I's tryin to run a business!