Tom Cruise fired up his Ducati and barreled out of a fancy Hollywood hotel late last night with a BRAND NEW CHICK ridin' on the back ... at least we think it was Tom Cruise ... LET'S INVESTIGATE!!!

Here are the facts ...

We know ... a mystery man sporting a motorcycle helmet left the Chateau Marmont hotel around 11:00 pm with a woman on the backseat.

We could see the man's brow line and nose ... and they bear a striking resemblance to Mr. Cruise.



We also know ... Tom was in town Thursday night, because he was photographed at the L.A. Kings playoff game at Staples Center earlier in the evening.

Plus ... it's no secret that Tom has a penchant for riding Ducatis ... and owns a Ducati superbike ... though the bike he's usually photographed on does NOT have a backseat.



As for the chick ... we don't know squat about her.

We called Tom's rep who insists it's NOT Tom -- Still, we gotta ask ...

Dear Rihanna,
Please provide Chris Brown frequent Instagram reminders of what he's no longer tapping -- such as your barely covered ass -- since he was stupid enough to break up with you.
Love,
The Internet (and everyone who uses it)

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And now, definitive proof Arnold Schwarzenegger and Maria Shriver are definitely maybe BACK TOGETHER -- Arnold totally grabbed Maria's butt last weekend ... and TMZ has video.

As we reported, Arnold and Maria were attending their daughter Christina's graduation at Georgetown ... and while people were milling around everywhere, Arnold casually cupped Maria's backside. It's subtle, but it happened.

FYI, Arnold has been obsessed with Maria's caboose since he met her in the '70s -- in fact, Arnold recently told a story on "60 Minutes" about how he told Maria's mother her daughter had a "great ass."



TMZ broke the story ... Arnold and Maria have been putting off their divorce and there are two lines of speculation -- 1) they're so rich divorce doesn't matter ... and 2) they secretly want to reconcile.

This video seems to suggest the latter ... but we still gotta ask ...

One day after Lindsey Vonn was spotted playing mom by dropping off his kids with Elin Nordegren at school alone, Tiger Woods joined in on the child-rearing fun.

Looking like one big happy family, Tiger and Lindsey -- who have been dating for around 5 to 6 months -- made the early morning trek to drop off his adorable children at their Palm Beach school on Tuesday.

The athletic lovebirds are really committed ... to getting those kids to class on time.

Good news for fans of hot girls making out with each other -- Rihanna says she's totally down to suck face with Miley Cyrus ... just as soon as Miley calls her up.

So, WHY is Rihanna talking about girl-on-girl action with Miley, you ask??

Long story short -- someone asked Miley the same question (in reverse) recently and M.C. said she'd "definitely" makeout with RiRi.

So, we found Rihanna this weekend on her way out of Giorgio Baldi and asked if the hypothetical feelings were mutual.

... and they are! 

Now, we just gotta get the two of 'em in the same room ... with some Barry White ... and a camera.

In what appears to be their first public out since they split last month, Sharon and Ozzy Osbourne had lunch together today in Beverly Hills ... TMZ has learned.

According to our sources, the two dined at the Polo Lounge at the Beverly Hills Hotel. We're told Ozzy arrived first, accompanied by another man, and Sharon arrived a short time later.

The three dined at a booth inside, with our sources saying Sharon and Ozzy did not appear "romantic" ... rather more like a business lunch ... but the two were definitely talking.

As TMZ first reported, Sharon has been telling friends she would not consider getting back together with Ozzy until he proves he's sober for good this time. Last month, Ozzy wrote on Facebook that he had been sober since early March ... so if he has stayed clean, he'd be about 2.5 months sober now.

Time will tell if that's proof enough for Sharon that Ozzy has changed his ways.


UPDATE 2:20 PM PT -- One source tells us that by the end of the lunch, Ozzy and Sharon were "cozying up together in the booth."

It's official ... Justin Bieber and Selena Gomez are officially a pair once again!!!!!!!!! At least in their seats at the Billboard Music Awards this weekend.

Photos of the seating arrangements have surfaced on the Internet -- and you can plainly see, Justin and Selena will be seated next to each other at the award show on Sunday.

And for anyone thinking it's an accident -- celebs can easily request to sit apart from people if they really want to ... so it's obvious, neither Justin nor Selena had a problem being so close to one another.

Justin and Selena split last year, but ever since then they've been on-and-off-again more than Lindsay Lohan's movie career -- so this could finally be a sign they're back together.

OR IS IT???

Breathe easy, James Deen ... Farrah Abraham is NOT PREGNANT ... not even a little bit, as far as she knows.

The "Teen Mom"-slash-porn-star pre-taped an episode of upcoming conflict resolution talk show "The Test," where producers convinced her to take one -- and it was NEGATIVE. (Trust us, that's a POSITIVE).

TMZ broke the story ... Abraham said she missed her period after making her porno with Deen. She was photographed while plunking down cash for an EPT at the drug store.

But Farrah told "The Test" host Kirk Fox that she never took that test (her explanation was WAY too convoluted to make any sense ... so we're going with "not enough cameras around").

We're told Farrah reacted indifferently. We can relate.

Rocky's boxing gloves ... Dorothy's ruby slippers ... Indiana Jones' bullwhip ... the bikini Farrah Abraham wore on the cover of her sex tape -- one of these pieces of cinema history CAN BE YOURS!!! --- take a guess which.

Vivid Entertainment -- the porn studio behind the release of "Farrah Superstar: Backdoor Teen Mom" -- listed Farrah's pink crystal-encrusted two-piece on eBay at midnight ... and bids started at $500.

It's pretty hilarious ... the listing advertises the Poolside Collection bikini as "used" -- we're told that means exactly what you think it means: the bikini wasn't washed since Farrah wore it.  Think Monica Lewinsky and The Gap.

In fact, we're told the bikini shows overt signs of wear, including fake tan stains and glitter from Farrah's body lotion.

As the listing goes ... "Farrah's bikini ... straight off Farrah's body and into your hands."

As if your hands won't already be busy enough.

Tiger Woods lost the shirt off his back ... and this time his ex-wife Elin Nordegren had nothing to do with it.

The 37-year-old golf star aired out his man nipples and soaked up the sun by going shirtless on his yacht in Palm Beach on Tuesday.

While his fancy schmancy boat is called Solitude, Tiger spent the afternoon lounging and fishing with his two adorable kids and his sexy bikini-clad girlfriend Lindsey Vonn yesterday.

Although he's no stranger to being in the heat, hopefully Tiger used protection.