“The 4/20 Massacre” (*1/2 out of four) was a none-too-potent horror thriller about five young girls (Jamie Bernadette, Vanessa Rose Parker, Stacey Danger, Justine Wachsberger, and Marissa Pistone) who go on a camping trip in the woods when they stumble on a marijuana-growing operation run by a backwoods slasher whose a nutjob. A few gory kills stand out but otherwise you’d be better off watching “Deliverance”, “Mother’s Day”, or even “Half Baked”. The killer’s hilariously awful makeup makes him look like “Swamp Thing.”