34. Schoolly D, "P.S.K. What Does It Mean?"
"This birthed gangsta rap," Questlove said. "N.W.A just took this formula and ran with it." The Philly rapper's 1985 joint takes its name from a local gang, Park Side Killers, and its wicked "Sucker MCs"-style beats from an evidently stressed-out Roland 909 drum machine. In a lazily menacing flow, Schoolly buys coke, parties with a hooker, buys weed and goes to the club, where he finds an MC biting his style. "Put my pistol up against his head," he matter-of-factly explains. That he decides not to pull the trigger makes the jam no less chilling.