Lil Wayne|Tha Carter III | Cash MoneyWhen New Orleans’ Hot Boys formed in 1997, few foresaw teenager Lil Wayne — the youngest of the four — as the group’s eventual superstar. In a field of overbuilt masculinity, Wayne’s punishingly scrawny frame projects a bizarre range of excitable flows, featuring slurred runs, overenunciated croaks and off-and-on faux-Jamaican patois. In body and voice, Wayne suggests a hip-hop Muppet. Yet in spite of — or because of — that, few contemporary rappers are more fun to listen to. Giddy fun. Giggling, “OMG, did he just say that?” fun. Wayne has a penchant for outrageous similes, several of which can be found on his new disc, Tha Carter III. On “Dr. Carter,” for instance, he boasts, “Swagger tighter than a yeast infection/Fly/Go hard like geese erection.” Even when not deliberately humorous, Wayne’s myriad verbal “looks” and joy of hyperbole convey a sense of play that’s scarce among self-serious, scowling peers. As Wayne posits on “Phone Home” (strangest rap invocation of E.T. ever): “We are not the same, I am a Martian.” Who’s to argue?Such eclecticism flourished amid the raging flood of Wayne’s mixtapes since 2005’s exceptional Tha Carter II. Mixtapes are, of course, de rigueur these days, especially after fueling 50 Cent’s meteoric rise in the early 2000s, but Wayne’s mixtape output is breathtaking by any standard. Last December, Vibe.com annotated “The 77 Best Lil Wayne Songs” from 2007 alone. That included tracks from self-produced mixtapes (Da Drought 3 being the best), plus scores of unauthorized volumes. Some are simply mixtapes made from other people’s mixtapes. Such bounty creates challenges for Carter III, especially when “official” CDs and “unofficial” mixtapes are increasingly indistinguishable to all but the Recording Industry Association of America. Carter III invites comparisons to the preceding Carter volume but also to his myriad mixtapes. On both counts, the new CD falls short. It lacks the overall consistency and polish of Carter II,and against his mixtapes’ freewheeling spontaneity, Carter III sounds stilted and coldly deliberate. There’s a requisite T-Pain/strip-club anthem (“Got Money”), a cautionary, baby-don’t-wrong-me radio track (“Comfortable”), Wayne’s playful (though questionable) forays into Auto-Tunia (“Lollipop,” “Nothin’ on Me”), even post-Katrina social critique (“Tie My Hands”). As per Wayne’s gift for unpredictability, the finer moments are least expected. “Dr. Carter” is a throwback in which he metaphorically shock-paddles a comatose hip-hop back to life. “A Milli” lumbers on producer Bangladesh’s hypnotic vocal loop, while Wayne dribbles intricate doublets and triplets. Most impressive is “Let the Beat Build,” a gospel-fueled Kanye West production whose entire momentum is one of patient uplift and transcendence.Carter III is hardly a mess — most of the album is entirely enjoyable — but the more middling material inspires the inevitable thought: “This is cool, but it’s not topping ‘Upgrade U’ or ‘I Feel Like Dying’?” (two notable mixtape cuts). It’s a gift and a curse that Wayne’s songs, freely given, can best those he’s selling. (In a further, ironic twist, Wayne recently declared, “Fuck mixtape DJs,” and DJs retaliated by leaking his album online.) Undoubtedly, Wayne helped to create the conditions that now threaten his album’s reception. But don’t accuse him of spoiling his own party by being too prolific. Any two-bit rapper with Pro Tools and a CD burner can create box sets of material. Wayne didn’t achieve his stature by flooding the market; he did it by masterfully generating demand for his strange brew of eccentric braggadocio. Those voracious appetites may now indiscriminately feast on his content — legal, unofficial or otherwise — but, as Wayne’s forgotten lessers can attest: It’s better to be too desired than not at all. —Oliver WangLil Wayne performs at the House of Blues on Sunset on Monday, June 16.