Casper Smart is like a gremlin ... whatever you do, DON'T GET HIM WET!

With the rain coming down pretty hard in NYC on Wednesday, J.Lo's boy toy was safely sheltered from the elements with TWICE the amount of umbrella assistants as Jennifer.

Being the luckiest backup dancer in the world has its perks ... for now.

Marc Anthony and his kids hit up Disneyland with his new girlfriend who is both hot and billionaire-adjacent.

The new GF is Chloe Green, daughter of UK billionaire Sir Philip Green, whose estimated net worth is $5 billion.

It's a good bet Sir Philip provides his daughter with an endless supply of loot. He reportedly dropped $6 million on his son's Bar Mitzvah -- a lot more impressive than a bunch of useless savings bonds.

In related news ... Casper Smart just got a big raise in his allowance.

Marc Anthony isn't just on good terms with his estranged wife Jennifer Lopez ... he's also on good terms with the guy who's bangin' her ... at least judging by this photo.

TMZ has obtained a photo of Casper Smart in a great, big bro hug with Marc at a private airport in NY yesterday.

We're told the kids -- Emme and Max -- have been hangin' with J.Lo and Casper during the most recent leg of Jenny's international tour ... and when they arrived back in the States on Monday, daddy was right there to greet them.

Sources tell us ... things seemed very friendly and the kids appeared happy to see their dad.

Marc Anthony held out hope for a reconciliation with Jennifer Lopez, but decided to file for divorce when she told him ... she's madly in love with BF Casper Smart ... TMZ has learned.

TMZ broke the story ... Marc filed for divorce Monday -- nine months after the couple announced they were splitting.

But sources extremely close to Marc tell us, he didn't make the decision on his own -- he had a heart-to-heart with J.Lo a few weeks back to see if she really, truly wanted to end the marriage.

We're told he said he wanted to give the marriage another try, but Jennifer confessed ... she was deeply in love with Casper ... and wanted to pursue that relationship.

We're told Marc was blindsided ... he had not idea things were so serious -- and he was hurt.

So that's why Marc filed divorce papers this week.

Jennifer Lopez is drawing a line in the sand -- paying nearly a grand to rent out a public beach in L.A. last weekend ... to keep randoms away from her family and children.

Sources tell TMZ, Jennifer forked over $925 to the city of Long Beach to rent out Marine Beach on Saturday -- 3,400 feet of shoreline -- just for her, her kids, her BF Casper Smart and other family and friends.

To keep out the riffraff, we're told lifeguards marked off the water using buoys -- and kept the beach gates locked.

We're told J.Lo and co. brought their own jet skis for awesome fun times -- and even hired a wakeboard instructor.

Meanwhile, a bunch of sad locals stayed home and played with dirt.

Jennifer Lopez and her 24-year-old boyfriend Casper Smart were quite the lovebirds and enjoyed a Valentine's Day frolicking on the sand in Santa Barbara on Tuesday.

Besides holding hands and taking long walks on the beach, Jen even climbed up on top of Casper to ride the swing together.

In related news, Marc Anthony VD pics should surface in 5 ... 4... 3 ...

Jennifer Lopez showed off her 42-year-old mother of two taut flat stomach while in Malibu the other day.

The "American Idol" judge was looking belly good, as her 24-year-old boy toy lover Casper Smart frolicked on the sand with her daughter Emme.

Ticking off Marc Anthony is like a day at the beach.

Marc Anthony and Jennifer Lopez possibly getting back together means only one thing -- J.Lo's boy toy Casper Smart better enjoy the Bentley and those sweet vacas while he can! Tick, tock ...

Jennifer Lopez might want to think twice about handing Casper Smart the keys to her Bentley ... 'cause her BF just pleaded no contest in a drag racing case.

Casper's high speed bust came back in April 2010 -- long before his J.Lo days -- and today an LA County Superior Court judge hit him with 12 months probation and a $500 fine.

Casper wasn't required to be in court ... his attorney entered the plea. We're guessing speed racer had better people things to do.

With their Florida getaway still in full effect, Jennifer Lopez made sure to hold her boy toy Casper Smart's hand to safely maneuver down Miami's Lincoln Road this weekend.

The 24-year-old better know to look both ways before crossing ... J.Lo.

Boy toy extraordinaire Casper Smart is really cruising into Jennifer Lopez's life ... and rode around on a yacht with the pop icon and her two kids in Miami on Friday.

For J.Lo, 2012 is all about out with the old and in with the new ... arm candy.