Paparazzi Photo

Police in Norway are on the verge of declaring a state of emergency in Oslo, after tens of thousands of unruly Justin Bieber fans overran the city -- and now, they're begging the singer for help.

Justin's scheduled to perform 4 new songs tonight outside Oslo's famed opera house as part of his "Around the World" TV special -- and we're told crazed Bieber fans from all over Europe have descended on the city for the event.

We're told the crowds have swelled to such overwhelming numbers, the police lost control -- and are pleading with Bieber to take the stage early ... before all hell breaks loose ... as in RIGHT NOW.

Bieber's aware of the situation -- he just tweeted, "...for the show to happen u must all listen to the police. we are all concerned for your safety and i want what is best for u. please listen."

Bieber is currently in a secret location and will be helicoptered to the stage.

Story developing ...

Mark Zuckerberg desperately needed to refill his wallet in Italy yesterday -- stopping by an ATM on the island of Capri ... after losing $1.5 BILLION on his plummeting Facebook stock ... in a matter of hours.

Facebook shares dropped 9.6% yesterday, finishing at a new low of $28.84 -- reducing Mark's net worth from $16.2 billion to $14.7 billion. All told, yesterday's drop raised the stock's losses to 24 percent ... making it the worst-performing large IPO in the last decade.

Yesterday's drop also cost Mark his spot on the world's 40 richest people list.

Ousted "X Factor" judge Nicole Scherzinger refused to take a stand on Britney Spears this weekend in Italy -- dropping to her knees while sunning herself on vacation with her Formula One driver boyfriend Lewis Hamilton.

Who are we to judge?

Mark Zuckerberg and Priscilla Chan paid a visit to the Sistine Chapel in Vatican City over the weekend ... where they gazed at one of the most famous works of art in the history of the world -- The Creation of Adam, courtesy of Michelangelo.

Mark looked duly impressed, but we gotta ask ...

Mark Zuckerberg ditched his hoodie for a more grown up, married look ... as he and Priscilla Chan strolled on a cobblestone road on the Amalfi Coast in Italy.

It's the second leg of their honeymoon -- they just left Rome.

Good to see Mark smiling, in spite of the fact that his fortune sank from $20 billion to around $17 billion.

Halle Berry went au naturel at the beach this weekend -- not in a topless way -- but in a badass 70s hairstyle kinda way.

Halle and fiance Olivier Martinez took a romantic stroll ... and flashed her massive emerald engagement rock in Malibu.

Halle's been very vocal about her desire to move to Olivier's native France ... partially to escape the paparazzi in Los Angeles -- but she looked pretty chill this weekend, sporting her curly 'do.

Mark Zuckerberg and Priscilla Chan blended with the crowd during their honeymoon in Rome -- as best as a gazillionaire can blend.

It looks like they didn't attract much attention -- in fact, they seem to go unnoticed by most people in the crowded restaurant in the middle of the famed city.

Ray J seemed in good health as he and a pal did a little shopping in Beverly Hills yesterday afternoon ... just a few days after he was hospitalized in Las Vegas.

As TMZ first reported, Ray J was taken to the hospital the morning after the Billboard Awards after suffering from a combination of exhaustion and dehydration. It was Sophie Monk, who endorses an ingrown hair removal product with Ray J, who discovered him in his hotel room and called 911.

She's baaaaaaaaaaaaack ... Britney Spears just showed up for the second day of filming "X Factor" in Austin, Texas today -- wearing the same dress as yesterday ... for continuity.

It should be exciting ... at least if it's anything like Britney's first day -- when the singer walked off the set in the middle of auditions, disappearing for four full performances.

Some sources say Britney was upset over a contestant's rendition of her song "Hold It Against Me." Others say Britney just needed a break.

But it doesn't matter -- as we first reported, Britney's got "X Factor" over a barrel ... locking down a contract that pretty much allows her to do whatever the hell she wants.

3:37 PM PT -- That's a wrap for now. The judges just finished one of today's tapings and waved goodbye to the audience ... check out all those Apple products.

3:32 PM PT -- Britney just said yes to a contestant the other three judges rejected -- saying, "I'll sign you personally, sweetie." One problem ... Britney doesn't have a label.

2:25 PM PT -- We're told Britney has had a great start to the day and seems much more confident -- even getting so bold as to disagree with Simon. She did take one short break, about five minutes, and she missed one audition ... which everyone on set was totally ok with.

1:50 PM PT -- ALL the judges are wearing the same outfits as yesterday -- and sources tell us, the reason is producers didn't get all the shots they needed on the first day of filming ... and need to fill in some gaps.

Britney already seems to be in better spirits today than yesterday ... spotted dancing behind the judges' table with Demi Lovato with Simon Cowell sitting beside them.

Jimmy Fallon got two big eyefuls at a signing for his new book "Thank You Notes 2," when a fake mustached fame-hungry female "fan" went topless at a Barnes and Noble in Manhattan on Thursday.

Turns out the streaker is this chick named Holly Van Voast, who has been known to get attention by flashing her lady goods in public before. Just a few months ago, the peroxide blonde was arrested for baring her knockers inside NYC's famed St. Patrick's Cathedral.

Using their powers of camouflage, Malia Obama's Secret Service detail managed to go totally unnoticed at a tween-filled One Direction concert Thursday night ... well, ALMOST unnoticed.

While President Obama's 13-year-old daughter screamed her face off at the Patriot Center in Fairfax, VA ... one of her protectors kept his eyes peeled for danger while trying to blend in with the army of screaming teenage girls.

Auditions are set to kick off any minute at the Erwin Center in Austin -- and we're told Britney's fellow "X Factor" judges Simon Cowell and L.A. Reid are there too.

Demi Lovato also showed up ... and got dissed by a fan holding a sign that says, "Go Britney."

Tara Reid has come a long way since 2006 -- when Kim Kardashian famously left her in the dust outside a hot Hollywood nightclub -- in fact, just last night, Tara actually exchanged WORDS with the reality TV queen.

It's a video from the annals of TMZ history -- a young and nubile Kim Kardashian walking arm-in-arm with Paris Hilton into Hyde nightclub in 2006 ... breezing straight past Tara Reid, who'd been forced to wait in line.

But last night in Cannes (on Diddy's yacht) -- we're told Kim actually acknowledged Tara's existence, even speaking to the "American Pie" actress for several full minutes.

And to bring it all full circle -- Paris Hilton was there too!!! But we're told Kim didn't spend much time with her.

So we gotta ask ...

If Mark Zuckerberg's new wife was expecting a MASSIVE diamond on her wedding ring ... she was SORELY disappointed.

Just days after the surprise wedding of the century, Priscilla Chan-Zuckerberg took her brand new ruby rock on the road ... flashing her piece during a lunch date with a friend in Palo Alto, CA yesterday.

According to reports, the $20 BILLION Facebook honcho -- who has a reputation for not caring about excessive displays of wealth -- designed the ring himself.

So, we gotta ask ...

Breakups do a body good ... especially for Elin Nordegren ... who was flaunting her bikini hardbody just days after ending things with her Tiger Woods rebound guy Jamie Dingman.

The Swedish 32-year-old mother of two was hanging out in Miami this weekend ... after announcing her 1-year relationship with the wealthy businessman officially hit the skids.

Since divorcing Tiger, Elin has been busy buying a new $12 million North Palm Beach estate and then leveling it to build her dream home from the ground up.

Elin definitely looks like $100 million bucks.

Kim Kardashian and current boyfriend Kanye West continued their trip to London by embracing their monochromatic differences -- KK decked out all in black, KW all in denim blue.

Kim has been in town to promote the upcoming season of "Keeping Up with the Kardashians" and attend the FIFI UK Fragrance Awards.

Kanye has been in town to watch Kim promote the upcoming season of "Keeping Up with the Kardashians" and attend the FIFI UK Fragrance Awards.