Grungy type look.

I'm a 21 year old guy and I've been growing my hair our for about a year(I was bald a year ago). Anyways my hair is really boring and I wanted to get kind of the shiny clumpy look to my hair kinda like Kurt Cobain has in that picture. I've asked some of my friends that know more about hair then me and I've had advice ranging from "just don't wash it or get it wet and put all the crap you want in it till its so dirty that it clumps up and looks like that" to "wash it and condition it then put in a massive amount of wax." Any advice would be greatly appreciated.
Jim