Balding and curmudgeonly, Missouri rapper and recent Rhymesayers signee Mac Lethal speaks for everyone who came of age on ’90s hip-hop but can’t muster the same excitement for current pop music. He raps extended, insult-comedian tirades against modern R&B singers like T-Pain and Ciara and pop starlets like Stacy “Fergie” Ferguson (“She smokes meth—look it up on Wikipedia!” he’s been known to shout at his shows) and, as if to prove his allegiance to the bygone era of his youth, last time he played Milwaukee he rapped the Konami Code: “Up, up, down, down, left, right, left, right, B, A.” He returns tonight for a 9 p.m. show at Mad Planet.