Bad marijuana, usually brown with tons of seeds and stems. Very harsh on the lungs, hence the word blowout. You have to inhale the smoke and hurry up and blow it right back out. There's no holding it in like if you were smoking the kind. It costs $5 for a 1 to 2 gram bag of it, compared to $20 for a 1 gram bag of that straight hydro sticky icky.
Damn, I wish I wasn't broke! Now, I gotta go down the street and get a bag of blowout from the A-Lons.