A way of life, living without care, not giving a fucking shit. Main stream describes it as a music genre but really most people who are grunge listen to alternative music mostly, along with rock metal and punk. Most of the style came from the west coast, Seattle being a major input but also Cali and Nevada helped with large populations of grunge.
Some of you almost got it. But the rest of you... Go fuck yourself, you will never get it.
Living a grunge lifestyle you do a lot less laundry.