Nurse!

Jason Derulo has a zero-tolerance policy for being mistaken for another R&B superstar -- so much so, he attacked 2 guys at a Las Vegas hotel for calling him ... Usher.

Law enforcement sources tell TMZ... cops were called to the ARIA hotel during the early hours of Tuesday morning after Derulo threw fists with the men.

Eyewitnesses tell us Derulo and one of the men were passing each other on an escalator when the guy seemed to troll Derulo by yelling, "Hey, Usher! F*** you, bitch!!!" That's when Derulo got pissed and punched him right in the face, sending the dude to the floor.

It didn't end there ... Jason allegedly also slapped the second guy moments later, and security had to step in to break up the scrum. You can see part of the fight in the video ... even though Jason was walking with a large dude, perhaps his bodyguard ... he still charged directly at the guys after the Usher line.

At the time, the 2 victims did not want to press charges, but there's always the possibility of a lawsuit. Either way, they have up to one year to change their minds and move forward with charges. Jason did get a trespassing notice from ARIA, and was removed from the property.

Cody Simpson's sister is beyond lucky to be alive after breaking her neck while diving into a pool, and as if that wasn't bad enough ... she tested positive for covid-19.

Alli Simpson was immediately taken to an Australian hospital in an ambulance on New Year's Eve... after diving head-first into a shallow swimming pool, and hitting her head on the floor. She ended up having 2 severe fractures in her neck.

The 23-year old opened up about the scary event ... posting photos from the ambulance and Gold Coast University Hospital -- outside Brisbane. She says, "I am extremely lucky to be alive and/or not quadriplegic as it JUST missed my spinal chord..⁣"

Though she didn't have to get any immediate surgery, she will have to live in a neck brace for 4 straight months ... all day, every day.

She admitted this was not the best start to the year for her, but she was mainly optimistic and shared her gratitude... "to say the least - I have a new lease on life & will be forever grateful that it was not worse!!⁣"

She thanked her family, friends and the medical staff for their support ... and left some encouraging words for us all going into 2022 ... "hoping the start to your year has been a whole lot better than mine!! stay safe this year fam & DON’T DIVE INTO ANYTHING WHEN YOU DON’T KNOW IT’S DEPTH!!! 🤍🤍🤍 "

As we reported, police in Naples, Florida shot and killed a Malayan tiger named Eko Wednesday night, after a custodian allegedly went into an unauthorized area and, according to cops, either tried petting or feeding the animal. Eko clamped onto the guy's hand, and you hear him wailing in pain as cops approached.

This video is hard to watch, but it shows the consequences when someone goes rogue and gets way too close to a wild animal.

Police are unable to free the custodian, and then they shoot the tiger in the head at point-blank range, killing him.

It's a terrible tragedy that has been repeated many times before ... where someone put himself/herself and the animal in danger by getting way too close.

So, you don't want to get the COVID vaccine because you don't trust the science ... well, here's an incentive -- you get the shot, you get to keep your hair.

Singer Ava Max says she's suffered hair loss after contracting COVID. She posted a vid Wednesday night, saying, "Baby hairs Comin THRU. "Also so so happy my hair is growing back. I lost a lot of hair when I had COVID last year!! :( "

Turns out ... the "My Head & My Heart" singer isn't making this up. According to the American Academy of Dermatology, hair loss is a consequence of the virus.

To be specific, the Academy says high fever from various illnesses, including COVID, can result in "noticeable hair loss."

It's actually not technically hair loss -- it's hair shedding. It typically begins 2 to 3 months after the fever subsides. Clumps of hair can come out after showering or brushing, and it can last for as long as 9 months before it stops.

A tiger was shot and killed Wednesday at the Naples Zoo after a zoo cleaner violated the rules by entering an area near the tiger he should never have been.

The man appeared to either be petting or feeding the tiger ... sticking his hand through the fence. The tiger grabbed the man's arm and attempted to pull him into the enclosure.

According to the Collier County Sheriff's Dept., deputies tried kicking the enclosure in an effort to get the tiger to release the man's arm ... but it didn't work.

A deputy then shot and killed the animal ... a Malayan tiger named Eko.

The man was a member of a cleaning crew at the zoo -- the crew was a third party, not an employee of the zoo -- and he was supposed to be cleaning restrooms and the gift shop, but decided to pet or feed the tiger instead.

Caitlyn Jenner's days as an Olympic star have caught up to her in a painful way -- in the form of knee replacement surgery.

Sources with direct knowledge tell TMZ ... the decathlon gold medalist went under the knife at Cedars-Sinai in L.A. December 14. We're told the surgery lasted 3 hours and so far, so good.

The before-and-after X-Rays pretty much tell the story.

Caitlyn's up and about again ... walking gingerly around her Malibu compound, where she's staying for at least another week before venturing out.

Her goal right at the start of 2022 ... to walk normally, drive and get back to all the stuff she likes ... including golf. She loves skiing -- something that was off the table before surgery -- but her goal is to hit the slopes next winter.

Famous boxing announcer David Diamante was reportedly critically injured in a serious motorcycle accident this week ... but thankfully, he's alert and in good spirits.

Diamante -- who's worked for ESPN, DAZN, Showtime, HBO, the Brooklyn Nets and more -- was riding on a street beneath the Brooklyn Queens Expressway when the accident took place, according to Boxing Scene.

The 50-year-old was rushed to a local hospital, where he was treated for multiple broken ribs and fractures to his spine, as well as "serious" damage to his knee, the outlet reports.

Diamante underwent a 5-hour procedure on Tuesday ... where screws, rods, and cadaver parts were placed in his spine.

But, the good news?? Diamante is already talking about kickstarting his recovery and getting back on his feet.

"It's going to be a tough road," he told the outlet. "It's a bad injury and getting better will take some time. This will be a struggle. I'll have to learn to walk again, and right now there's a risk of complications."

"But, I have a positive attitude and will be back as soon as possible."

Michael Buffer also says he spoke with Diamante ... saying his fellow announcer is "very optimistic."

"David’s a fighter and has met big challenges in his life-this will be another one!"

Diamante is a legend in combat sports ... and is known for his trademark phrase, "The fight is on." He most recently worked the Joseph Parker vs. Derek Chisora fight on Dec. 18.

Teddy Bridgewater was forced to spend Sunday night in a hospital ... after he terrifyingly slammed his head on the grass during the Broncos' game against the Bengals.

The horrifying scene all went down on Sunday in the third quarter of the game at Empower Field in Denver ... when Bridgewater dove for a first down but landed awkwardly on his head and neck.

Video of the play is scary ... you can see in the clip, Teddy appeared to be knocked unconscious as soon as his face hit the turf.

Trainers and staffers raced out to tend to the star quarterback ... removing his facemask and strapping him to a backboard, before taking him off the field and to a hospital on a stretcher.

Denver head coach Vic Fangio announced after the game Bridgewater would be kept at a medical facility for evaluation through at least Monday ... though he did say he expected the signal-caller to somehow be okay.

"Everything has checked out good up to this point," Fangio told reporters after Denver went on to lose, 15-10. "They're just going to keep him overnight for observations. But they think he'll -- should be and will be fine. Eventually."

Bridgewater is no stranger to horrible injuries -- you'll recall, he nearly lost his leg after he gruesomely tore his ACL in a play during Minnesota Vikings practice in 2016.

He's since come back from that injury strongly ... and had been having a solid year for Denver this season, recording 3,052 passing yards and 18 passing TDs.

Get well soon, Teddy.

Jake Paul is only 24, but he's suffering from memory loss and slurred speech, and it's largely because of boxing -- and it could get even worse with tonight's fight.

Jake appeared on "In Depth With Graham Besinger," and talked about something boxers rarely discuss when they're still in the game -- how boxing messes up their head.

Jake told Graham, "I notice it in conversations with like, with my girlfriend or friends, like, not remembering something that I should be able to remember that happened a couple days ago."

He went on ... "Sometimes in my speech, where like every hundredth or two hundredth word, I'll mess up or, like, slur, which I didn't do that before."

Jake says his problems actually started with football, but are clearly worsened by boxing. He doesn't even remember how many concussions he's suffered -- somewhere between 20 and 30.

Again, something boxers don't say ... Jake says he's scared about the long-term effects, although he thinks certain psychedelic drugs could help abate the problems.

It's pretty shocking he's saying all this when he's about to square off with former UFC Champ Tyron Woodley Saturday night. He beat Tyron by split decision in the past and the rematch promises to be fierce.

Jake said his doctor was blunt -- stay away from the ring, but that's not gonna happen.

Horrifying scene during the Chargers vs. Chiefs game Thursday ... L.A. tight end, Donald Parham, was rushed to the hospital after he violently slammed his head on the turf during a play.

Parham was attempting to catch a touchdown pass in the first quarter of the game at SoFi Stadium ... when his head forcefully hit the ground after he dove for the ball.

The 24-year-old appeared to be knocked unconscious immediately ... with his arms stiffening in the bent position.

Trainers rushed out to the football player ... and unscrewed his facemask, before securing him to a backboard and placing him on a stretcher.

Parham was seen moving his hands and legs while talking with trainers ... but, terrifyingly, his arms were shaking as he was being stretchered off the field.

The Chargers say he was ultimately taken to nearby UCLA Harbor Medical Center with a head injury ... adding that he was "in stable condition." No further update has been given.

"I'm just hoping for the best," star quarterback Justin Herbert said of Parham after the game. "Parham has been an incredible teammate and an incredible friend. He's been nice to everyone in that locker room, and everyone loves him."

Parham has started nine games for L.A. this season ... scoring three touchdowns.

The referee who was violently stabbed by a wrestler in the ring on Saturday actually agreed to take $75 to bleed during the match ... this according to cops.

A spokesperson for the Irving Police Dept. tells TMZ Sports ... officers spoke with the ref, Lando Deltoro, shortly after Devon Nicholson -- aka "Hannibal" -- repeatedly jammed an iron stake into his head at an independent wrestling event in Texas over the weekend.

The spokesperson says Deltoro told them he cut a deal with Nicholson prior to the match -- agreeing to dress up like a referee and then take hits to the head and gush blood in the squared circle.

The spokesperson says Deltoro told police, however, that the bit went too far ... and Nicholson actually ended up hurting him badly with the stake.

But, according to cops, Deltoro told them he did not want to press charges.

We also spoke to Deltoro on Wednesday, and he confirmed with us he was paid for the match, though he did not specify the amount. Deltoro also told us he did not agree to Nicholson's "extra" spiking.

As we previously reported, Deltoro suffered major head injuries as a result of the match, requiring sutures to close the open wounds in his head.

For his part, Nicholson says Deltoro gave him no indication during the match that he was being injured.

The Miz says the wrestler who repeatedly stabbed a ref in the head with an iron spike should NEVER be hired again ... telling TMZ Sports the dude should be perma-banned from the squared circle.

"You don't do that stuff," the WWE superstar told us out at LAX on Tuesday ... "That didn't look like a mistake."

If you missed it ... Devon Nicholson -- aka "Hannibal" -- badly injured a ref during a match at an independent event in Irving, Texas on Saturday.

In footage from the event, you can see Nicholson pounded on the guy's forehead with a stake over and over and over again -- 'causing the man to bleed severely in the ring.

The ref, Lando Deltoro, was eventually hospitalized over the incident ... though, thankfully, he's expected to make a full recovery.

When we asked The Miz about it all in Los Angeles just three days after the incident ... he said he'd be in favor of a lifetime ban for the wrestler.

"Accidents happen," The Miz said, "but I don't get stabbed with like a knife or whatever the hell the guy had."

For his part, Nicholson says he wasn't aware that he was injuring the ref ... saying Deltoro never gave him any indication that he was being hurt in the show.

As for Deltoro, he claimed he had no way of telling Nicholson to stop ... saying the wrestler was too big and too powerful to get any words out before he eventually slipped out of consciousness.

There was absolutely nothing scripted about the pain Kevin Owens felt after botching a front flip Monday ... 'cause the WWE superstar said his body hurt like hell after he violently bounced it off the ground during a match.

Owens was wrestling Bobby Lashley at the "RAW" event St. Paul, MN. ... when he tried to leap from the ring and flip into his opponent.

The problem? Lashley cleared out of the way well before Owens arrived -- sending the 6-foot, 266-pound wrestler crashing into the floor.

You can see in video of the failed move, Owens hit the deck HARD -- landing right on his lower back/tailbone.

"I often get asked what hurt me the most throughout my career and there's 2 specific things that always come to mind," Owens said. "but as of last night, there’s a new answer to add to that list because for some reason, this absolutely destroyed me."

To add insult to injury ... the 37-year-old went on to lose the match to Lashley.

BTW, if you were wondering -- the other two moves that Owens says hurt him badly both also consisted of him being hit in the back.

A train ride in New York turned violent for one woman, who got a hand to the face after getting into an argument with an alleged creep ... a guy NYPD's now trying to find.

The incident went down on a Brooklyn-bound subway line early Friday ... and as you can see in the video ... the man and woman were really going at it. The woman was seated and yelling at the guy who was standing over her and shouting back, "It's none of your business."

At one point, things escalate physically, with the guy smacking her right in the face ... and she lets out a scream.

Law enforcement sources tell us ... someone on the train reported this to cops shortly after it happened, and the victim suffered minor injuries and a pair of broken glasses. The man in question had fled by the time officers arrived.

As to what led up to this, we're told the woman allegedly saw the guy taking photos of women onboard, and she decided to do the same to him ... which apparently pissed him off.

A wrestler took things way too far during a match over the weekend ... stabbing a referee in the head with an iron spike so violently, the man was forced to go to the hospital.

The horrifying scene all went down at a World Class Pro Wrestling event in Irving, Texas on Saturday ... when Devon Nicholson -- AKA "Hannibal" -- was taking on "Carlito."

Nicholson -- who runs a popular YouTube page that has over 300,000 subscribers -- and Carlito put on a show for several minutes ... with Nicholson eventually pinning his opponent and winning the match.

Nicholson, though, did not leave the ring immediately -- and, instead, he began fighting with a referee inside the squared circle.

In video from the match, you can see at one point, Nicholson took out a spike and began ramming it into the ref's forehead over and over and over again.

The full video of the match shows Nicholson stabbed and scraped the man with the sharp object over a dozen times -- leaving him in a pool of blood in the ring.

Eventually, another wrestler pulled Nicholson off the ref -- and video from the event shows a public address announcer actually asked for a doctor in the crowd to help the ref.

The ref -- Lando Deltoro -- was ultimately taken to the hospital and required sutures to close his wounds.

Somehow, according to a statement on Deltoro's social media pages, he's expected to make a full recovery.

"Recovering at home," the ref said on his Twitter page. "Still a bit fuzzy and pain, yes lots of pain. But I'll live. Thanks you all for the outpouring of love and support."

World Class Pro Wrestling owner Jerry Bostic, meanwhile, said in a video message Sunday that he found Nicholson's actions appalling -- and announced the wrestler is now banned from all of his future events.

"World Class moving forward will not be associated with Devon Nicholson," Bostic said. "I cannot and will not condone what happened last night."

We've reached out to Nicholson for comment, but so far, no word back yet.

Terrible news in the horse racing world ... 3 jockeys were hospitalized and 2 horses died after a horrific fall during a horserace in Hong Kong on Sunday.

The tragic event happened during the Group 1 Hong Kong Sprint at Sha Tin Racecourse ... when jockey Lyle Hewitson's horse lost its footing several hundred yards into the race, collapsing ahead of a large pack of horses.

The whole incident was televised ... and the video clearly shows Hewiston's horse, Amazing Star fall, sending the South African jockey slamming to the ground, before being trampled by a stampede of horses.

That caused a domino effect ... and sent 3 other jockeys and their horses flying to the ground.

Hong Kong Jockey Club's executive director Andrew Harding says all 3 men were treated at Prince of Wales hospital with multiple injuries.

Hewitson ended up having a fractured hip and small bleed in the brain. 4x Hong Kong champ, Zac Purton, suffered four fractured ribs, a fractured wrist and a broken nose.

The third jockey, Yuichi Fukunaga of Japan, broke his collarbone.

Miraculously, all of the jockeys survived.

Unfortunately, the 2 horses weren't so lucky. Amazing Star and Naboo Attack suffered fatal injuries and had to be euthanized.

The race did go on after the collision. Australian jockey Blake Shinn and his horse Sky Field officially took the title ... a win he calls "bittersweet".

"I have mixed emotions for winning this race today," Shinn said.

"Obviously the first emotion is that my feelings are with the fallen jockeys and horses out there."