Sudden, all-encompassing celebrity often has a corrosive effect on pop stars, draining their subsequent work of vitality, humanity, and humor while infusing it with a fatal self-seriousness. So it’s a relief to report that Ke$ha, paradoxically, is a funnier, more melodically dynamic tart-diva in the wake of over-leveraged smash debut Animal. If that album was all chummy club beats and provocative look-at-me preening, follow-up Cannibal is a harder-edged comedy act: the beats, from Dr. Luke and others, have spikes — all the better to drive every puerile, tongue-poked-through-cheek punch line irretrievably home. “I’m not gonna sit here while you circle-jerk it and work it,” she smirks at some lounge lizard straw man on “Sleazy,” a Bangladesh banger that winks at early M.I.A. and Missy Elliott beats even as Ke$ha’s rhyming mimics Eminem’s needle-scratch, herky-jerk flow. The frantic title track delights in gratuitous double-entendres; “Blow” offers cathartically aerobic dance-floor world domination. Yet Cannibal turns subtly serious with “We R Who We R.” Thumping and anthemic, the single suggests a throwback to Animal’s whole-scale hedonism — until you realize she’s holding a mirror to the debauched, neon-lit wasteland she used to celebrate.