Bad grindcore sounds like rocks in a blender and the Cookie Monster yelling at you like he just stubbed his toe. Good grindcore sounds like bones in a blender, pulverized to a dust that your not-smart friends would snort like a line of coke. I’m Diet—four mystery-shrouded longtime L.A. punks—is good grindcore. They clock in two Descendents covers, totaling seven seconds. Comes in an origami package designed by a rocket scientist.