At Richard’s on Richards on Thursday, February 19

Keith Thornton was the original sci-fi rapper, the first hip-hop star to make nonsense fascinating. As a member of New York City’s Ultramagnetic MCs in the late 1980s, Keith forged a surrealist lyrical style to counter rap’s traditional street-level realism, exploring an inner and outer cosmos while his contemporaries amused themselves with guns, drugs, and women. The Bronx native might not have achieved the commercial renown of the golden era’s biggest stars, but his technique endures, both in his prolific (but spotty) solo material, and in the bugged-out antics of major-label acolytes Ghostface Killah and Lil Wayne.

Keith’s in his mid-40s now, and while his delivery isn’t as ferocious as it used to be, his subject matter has grown steadily weirder, incorporating a dizzying number of alter egos and convoluted sci-fi plot twists. His current tour is billed as a battle between his two best-known aliases, an alien gynecologist called Dr. Octagon and his sinister nemesis, Dr. Doom. On-stage last week at Richard’s on Richards, though, Keith wasn’t suffering from multiple-personality disorder at all. Where he’s been known to orchestrate live sex shows and give away fried chicken during concerts, here he played a simpler role—that of elder statesman celebrating his greatest hits.

His head sheathed in a babushka-like silver sequined scarf, his eyes hidden behind black wraparound shades, Keith sauntered on-stage and pulled the nostalgia card early, playing a suite of songs from 1988’s Critical Beatdown, Ultramagnetic’s seminal first album. Basking in the lively approval of an almost exclusively male collection of pot smokers, the New Yorker displayed an easy rapport with his sideman, Dennis Deft, and his DJ, KutMasta Kurt, a young producer who’s guided much of his late-career output.

After an overlong and inept freestyle interlude, Dr. Octagon took over, rendering songs from 1996’s Dr. Octagonecologyst, including his acid-trip ode “Blue Flowers” and the doctor-as-porn-star fantasy, “Girl Let Me Touch You”. The latter song kicked off an extended run of sex jams from Keith’s millennial Spankmaster phase, each wetter and raunchier than the last. On record, tracks like “G-Spot” and “Freaks” seem like ironic exaggerations of top-40 loverman songs, but at Richard’s the filth factor was overwhelming. That the MC lingered so long over so many pussy-eating anthems for a roomful of scruffy young men was more than merely weird; it was a black-comic masterstroke.

After all that sex talk, Keith and the crowd seemed spent, the rapper dispassionately running through a handful of songs from his most recent release (last year’s half-assed Dr. Doom 2) while the room slowly thinned out. Nothing the New Yorker ever records will match the best of his catalogue material, a fact even Keith himself seems to recognize. The rapper has always come off as hip-hop’s resident crackpot, but he’s with-it enough to realize that revival tours aren’t just for washed-up white rock stars anymore. For Sting and Don Henley, it’s a greedy cash-in move; for Keith, it’s a simple matter of survival. No one who contributed to his retirement savings last Thursday could begrudge him that.