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.

Italy is fitting, because Mark said "arrivederci" to around 3 billion bucks this week after his Facebook stock took a nosedive.

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.

There are worse people to owe a debt of thanks to.

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.

While Jimmy did seem to get a kick out of it, security promptly escorted out the buxom wonder.

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. 

So check out the photo ... and use your power of sight to SPOT THE AGENT!!

So it begins ... Britney Spears just showed up for the first day of filming for Season 2 of "The X Factor" in Texas -- wearing a slim-fitting breast-accentuating pink dress, black heels, and a big smile.

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." 

Always tough to be last.

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.

It's unclear how much the ring cost ... hopefully not much ... 'cause his Facebook stock has been sinking like Natalie Wood ever since it debuted on Friday.

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.

A day after his estranged wife reportedly hanged herself at her New York home, Robert F. Kennedy Jr. showed up at the property, looking distressed.

As we reported, the Westchester County medical examiner claims 52-year-old Mary Kennedy died yesterday as a result of asphyxiation due to hanging at her Mount Kisco home. The medical examiner hasn't specified suicide, but it's being widely reported Mary killed herself.

Mary and RFK Jr. were married in 1994. RFK Jr. filed for divorce sixteen years later in 2010. He's currently rumored to be dating actress Cheryl Hines.