When the 27-year-old trouble magnet did finally show up – descending from the rafters, dressed in one half of a ringmaster’s uniform — the crazy-big crowd of 20,004 greeted her with tender, ear-bleeding caterwauls of love. The crowd was made up predominantly of young women, almost all of whom (1) looked to be exactly 18-years-and-one-day-old and (2) haven’t yet learned to walk in their 6-inch heels. (As the father of daughters, well, the word is “conflicted.”)

Surrounded by all manner of masked, acrobatic brutes, Britney opened with the title track from new disc “Circus.” That immediately begged the question: Was she actually singing? Seeing as how she barely sings on her own albums — and that the giant video screens NEVER showed close-ups of her — rest assured she was using backing tracks and a whole lot of molar-rattling booty bass. Nah. No singing.

But as my 5-year-old likes to sass, “Hellooo, missing the point.” Brit’s job was to distract from her limitations, delight with her strengths: looking hot (and fit), having killer hair, and, during “Piece of Me,” writhing in, and on top of, a golden cage pushed by guys dressed like the Gimp in “Pulp Fiction.”

It was Cirque du Skanky, and usually the star was just too busy to sing. In between the scads of costume changes, almost all of which left her bottomless, there were shenanigans involving karate dudes, magic dudes, dudes on bikes, dudes doing push-ups. Give Brit credit: She’s an equal opportunity sex kitten.

Mouthing the words to the songs — “Boys,” the naughty “If You Seek Amy,” “Do Something,” all played at incredibly loud volumes — she kept moving, skipping from one end of the long, wildly lit stage to the other. Her show was segmented into chapters — “House of Fun, “Freakshow” — and yet despite the themes, her dance moves were never more complicated than an angry stomp, a dirty shimmy.

Honestly? She is a truly lousy dancer. Like, drunk-cousin-at-your-wedding lousy. That said, girlfriend strikes a mean pose, and each defiant bit of ‘tude drew more jubilant crowd hollers. For all her troubles, for all her scandal, Britney is adored by her fans and loved unconditionally. Twenty-thousand people just went absolutely crazy for her for an hour and 40 minutes. You get that, right?

Anyway, there were a few clever surprises. She turned “Me Against the Music,” previously a duet with Madonna, into a Bollywood number, a cool nod to the popularity of “Slumdog Millionaire.” She perched on a bejeweled umbrella for the ballad “Everytime”; just call her Scary Poppins. For “Breathe on Me/Touch of My Hand,” a bound, blindfolded Brit rode a spinning swing made of dudes.

At about the time the choreography started to lose its oomph, and Brit started to look tuckered (she resorted to a Rerun on “What’s Happenin’?” dance), she got around to her biggest hits: “I’m a Slave 4 U,” the great dancer “Toxic” and a remix of “…Baby One More Time.”

After robust chants of “Britney! Britney!” she returned for her encore, “Womanizer,” performed in a cop’s uniform with requisite nightstick.

As a concert, it was subpar. As a spectacle, it was better. But let’s be honest, the coolest thing about seeing Britney Spears is telling your friends about it Monday morning. So brag hard. Have fun.