Slim Fast

Kendall Jenner definitely knows how to celebrate milestones on social media. Right after ringing up 10 million fools followers on Instagram -- she posted a video that would make R. Kelly proud.

What? We mean she did a little bump and grind. Sickos.

28-year-old Venezuelan fitness model/Instagram star Michelle Lewin reminded everyone that bikini season is almost upon us ... by wearing one in Miami this week in a way few can.

Ashley Tisdale celebrated her bachelorette party with pal Vanessa Hudgens on a huge yacht in Miami -- and Ash made sure to flaunt her ass in a tiny thong before it's, y'know ... locked down for life.

Thanks, bikinis!

Justin Bieber's never-ending quest for street cred continued last night when he jumped up on stage with Rick Ross to serve as his hypeboy ... then grabbed the mic to rap over some 2Pac. Holla if ya hear me!

It all took place at a nightclub called Gotha Club located in Cannes. Bieber hopped on stage to join Ross as he performed, looking more like someone who got separated from his parents and wandered up on stage.

Later -- sans shirt, of course -- Justin decided to hop on the mic himself to rap over 2Pac's classic song, "Dear Mama."

Justin Bieber and Paris Hilton are NOT banging ... in fact, she couldn't stand to spend more than a half-hour with him because he wouldn't stop playing his own songs ... TMZ has learned.

Paris and Justin partied in Cannes Sunday night at Gotha Nightclub. There are reports that the 2 got cozy ... with the 33-year-old climbing into Justin's 20-year-old lap ... then leaving for his house.

But here's the deal. We're told 50 people went back to Justin's house -- Paris was never alone with him. And something else we were told ... she said the party was lame and couldn't stand the fact that Justin was playing his own songs ... so she left after half an hour.

Kendall Jenner was doing just fine during her introduction of 5 Seconds of Summer during last night's Billboard Music Awards ... when suddenly words became her enemy and the whole thing went to hell.

Jenner got through the first part without a hiccup, but suddenly got thrown off track ... which led to her blurting out, "Guys, I'm the worst reader!"

Jenner took to Twitter afterwards and seemed to blame her eyesight for the debacle, writing, "Anndddd as if I wasn't nervous already!!!! #NeverLeavinMyContactsAtHomeAgain! #LOL #LessonLearned"

Better luck next time.

The Internet thinks it has solved the mystery of the Solange Knowles/Jay Z elevator fight, but TMZ has learned the tweet is a fraud.

Shortly after TMZ posted the insane video of Solange losing it -- a photo of a tweet emerged in which Solange accuses Jay Z of hitting Beyonce ... and the image was forwarded over and over again yesterday.

But the tweet in question was never really posted on Solange's Twitter feed, and never even existed -- IT'S A TOTAL FAKE. Solange's rep tells TMZ, "I can confirm that Solange did not tweet that; that is not a real tweet."

But as far as theories go ... it's worth noting that Solange has deleted all Instagram photos with Beyonce in them ... except for one.

The mystery lives on ...

Kylie Jenner helped tattoo her initials on the hand of Lionel Richie's son ... which is both stupid and not entirely legal ... and TMZ has the video.

It all went down at a recording studio in Hollywood on Friday night. According to our sources, Kylie was there with sister Khloe Kardashian, French Montana and Miles Richie.

We're told Miles (who is 19) was getting ink from John Petro, who has tatted up the likes of Soulja Boy and Lil Wayne ... when Kylie decided she wanted to help out.

Sources say Kylie threw on some gloves and put her hands on top of Petro's as he administered the tat -- sorta like when a father lets his kid sit in his lap and "drive" a car.

But according to the LA County Dept. of Public Health, only people over 18 can give tattoos -- or even participate in the process -- and Kylie is only 16.

If authorities decide to go after Jenner, she could be hit with a misdemeanor and fined up to $1,000 ... and Petro could have his license suspended.

As for Richie ... well his punishment lasts for eternity.

Being friends with Kim Kardashian ain’t cheap since she insists on constantly getting married and having bridal shower after bridal shower after ... y'know.

Seriously, Kim ... the useless gift industry (looking at you, gravy boats) thanks you.

George Clooney and Amal Alamuddin celebrated their engagement in Malibu this weekend with a few close friends ... like Cindy Crawford, Rande Gerber, and a little guy known as Bono.

Our Bieber sources say Justin has been like a big brother to Madison for 2 years, and this was meant to be nothing more than a sweet photo of 2 people who have grown close. They say Justin has helped mentor Madison in her singing career.

Underage girls are all the rage -- days after 13-year-old Willow Smith posed in bed with a shirtless older man ... 20-year-old Justin Bieber came within inches of mashing his face into a 15-year-old girl's breast.

Bieber posted the photo of himself Thursday night, posing with up-and-coming singer Madison Beer and her left boob. Any closer and he might get himself in trouble.

You'll recall, Willow Smith ruffled some feathers with a recent Instagram photo, showing her lying in bed with shirtless 20-year-old actor Moises Arias.

The irony: Bieber's too old for Beer, but too young for beer.

The prosecutor who has been investigating the Justin Bieber egging case has told the victim ... "If this isn't felony vandalism, nothing is."

The neighbor tells TMZ ... the deputy D.A. in the Van Nuys office that was assigned the case called Justin's former Calabasas neighbor last week, and made his view clear ... a mere misdemeanor charge would be outrageous. We're told the deputy said, "If we don't charge him with a felony we ruin precedent for every other felony case we want to charge."

TMZ broke the story, Justin allegedly egged the neighbor's house in January. We posted a video in which you hear the singer goading the neighbor in the middle of the attack. We also reported cops have surveillance video clearly showing Justin smack in the middle of the scene at the time of the egging.

The neighbor and his 13-year-old daughter say they were face-to-face with Bieber during the attack, and saw him clearly. The neighbor has submitted bills totaling $20K to repair the damage.

The case has dragged on for months. We're told the deputy D.A. told the neighbor the file has now been sent downtown where it's being reviewed "at the highest level." We're assuming D.A. Jackie Lacey herself will make the final call.

Sources say the office has been split over whether to charge Bieber with a misdemeanor or a felony, but the guy who handled the case has a clear view ... it's a FELONY.

You're not the only one who can't pronounce Cara Delevingne's name -- Reese Witherspoon can't either, neither can Kate Upton or Zooey Deschanel ... and they all proved it during a hilarious drunk elevator ride earlier this week.

Cara posted the footage to her Instagram account after an evening at the Met Gala Monday night -- showing the hottest group of women ever to assemble in an elevator, and they're all joking about how to pronounce Cara's (Cah-ra's?) name.

The video is hilarious -- but the award goes to Reese for her attempt ... "Delevig-ny."

Cara has since deleted the footage -- but here they are again in all their glory.

Kim Kardashian and Kanye West can't get married, because their prenup is still being hashed out ... TMZ has learned.

Sources connected with Kim and Kanye tell TMZ ... the prenup won't be signed until next week -- probably Wednesday at the earliest. We're told the marriage will NOT take place until both sign on the dotted line.

Our sources say -- unlike Kim's prenup with Kris Humphries -- the current negotiations are friendly ... there's no fighting. We're told there's just a lot to work out, and it got complicated by the fact that Kanye recently changed management.

As for the wedding ... it's looking like Paris ... around Memorial Day.

Jada Pinkett Smith was locked and loaded Wednesday ... telling photogs the pic of her 13-year-old daughter in a bed with a 20-year-old guy was innocent ... and we're all "covert pedophiles" for thinking otherwise.

Jada arrived at LAX for a trip to NYC ... and she was brimming with anger, knowing we'd ask about the pic of Willow and her friend, "Hannah Montana" star Moises Arias.