If you’ve never been to the Slip Inn, you’ll have misgivings when you roll up to the red-neon-lit door of the tiny dive snuggled up next to a Save-Way with bars on its windows. Ignore those misgivings. The DJ starts spinning every night at 10. Don’t arrive much later than that, because the tiny, L-shaped place gets crazy packed. Expect a mixed crowd, from well-dressed Parkies slumming it to baggy-pantsed punks on the make. They are black, white, and Hispanic, all shaking their stuff to old-school and current hip-hop and rap. Plan to take a cab home.