They love to see her lip-sync

Showing off a newly chiseled physique and looking delighted to be performing for a live audience again, Britney Spears took the stage Thursday night at West Hollywood’s House of Blues to ecstatic applause from a sold-out crowd. It was her third “secret” show in as many consecutive nights after a three-year touring hiatus.

The singer may not have totally banished doubts about her future longevity as a platinum-selling, stadium-packing singer. But her “comeback” -- if you want to call it that -- cemented Spears’ place as pop music’s reigning drama queen, capable of capturing worldwide tabloid headlines with a bare minimum of creative expenditure.

Her unpublicized performance -- as part of an outfit billed as the M+M’s that consisted of Spears and four female backup dancers, who together resembled a younger, more ethnically homogenous version of the Pussycat Dolls -- was virtually identical to both the set she performed Tuesday at the San Diego House of Blues and Wednesday at the venue’s Anaheim branch. The M+M’s are scheduled to perform at the Las Vegas House of Blues on Sunday.

Attired on all three occasions in a brunet wig, knee-high go-go boots, a micro-miniskirt and a fur coat that concealed her pink rhinestone-encrusted bra for half the show, Spears did a bump, grind and lip-sync to several of her most familiar songs, including “Baby One More Time,” “I’m a Slave 4 U,” “Do Something” and “Toxic.”

With so much advance buildup, everyone knew what to expect the third time around.

“No lip-syncing, Britney,” warned Sylvie Vie, 22, from Pasadena, before the Thursday show. “If you do, I might have to throw a beer on you.”

No beverages were hurled, but someone in the audience that night apparently threw an unidentified object at Spears about halfway through the performance, a guard said. She was whisked offstage by security and the offender was hustled out of the venue. But the singer, apparently unhurt, came back a moment later to finish the set.

The pop star’s erratic behavior this year -- attacking a car with an umbrella, her notorious pre-rehab head-shaving incident, her sudden fondness for ill-fitting wigs and transparent clothing -- did little to diminish her fans’ ardor.

“She looked so freaking hot,” Julie West, 16, of Manhattan Beach said after Wednesday’s show. “Wig and all, I love it.”

To wit: On all three occasions, the crowds chanted the singer’s name -- “Brit-ney! Brit-ney!” -- as she reclaimed center stage. And at all three dates, she whipped the crowd into a frenzy by having her dancers pluck a man from the audience and position him on a chair for a brief lap-dance.

Spears’ performance Thursday lasted all of 14 minutes -- six minutes shorter than the Wednesday gig -- although, judging by the packed house’s rapturous applause and the unquestioning, fire-drill-like haste with which they exited the auditorium, that was enough for most in attendance.

On Tuesday, fans -- several of whom admitted paying up to $500 for scalped tickets -- massed outside the San Diego venue hours before Spears’ rumored arrival.

Even with a full complement of paparazzi documenting her every visit to Del Taco and incidents of “going commando” (that is, underwear-less) while out on the town in a mini-dress, the recently separated mother of two has been at work on new music and honing her stage act since being discharged from rehab in March.

She worked on new material with producer Jonathan “JR” Rotem -- with whom she has been romantically linked and who also produced much of the album by estranged spouse Kevin Federline -- as recently as last Saturday. And she’s already laid down five songs with songwriter-producer Sean Garrett -- responsible for hits by artists such as Chris Brown, Destiny’s Child and Ciara -- and plans to return to the studio with him next week to record three more.

“She’s back, totally focused on this new endeavor,” Garrett said Tuesday. “She’s worked really hard.

“She’s looking great. This new stuff is going to sound like ‘Toxic’ times 10,” he added, referring to Spears’ 2003 song.

Over the last month, the singer has been regularly attending dance classes at the Millennium Dance Complex in North Hollywood -- perhaps responsible for Spears’ newly toned abs.

“She’s done a lot for herself,” Garrett said. “People are going to be surprised. The best is yet to come.”

Marcy Saylor, 17, of Northridge, won her ticket to see the M+M’s Wednesday by calling in to KIIS-FM (102.7) two days earlier; the station hyped the gig as a “secret show for Britney Spears.” And although Saylor described herself as a onetime Spears fan, she admitted she was drawn to Wednesday’s performance more out of morbid curiosity than any appreciation of the singer’s music.

“I’ve known her since her first record, and I kind of grew out of it,” Saylor said before the show. “But I really want to see her wig fall off.”

After Thursday’s show, Hillary Tedeschi, 18, of Woodland Hills gave Spears’ comeback a qualified thumbs up.

“She’s back. She’s a good performer and deserves another chance,” Tedeschi said. “But she’s usually so full of surprises. It’s weird that she keeps performing the same exact show over and over.”

chris.lee@latimes.com

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Times staff writer Yvonne Villarreal contributed to this report.