Justin Bieber & Selena Gomez

Justin Bieber and Selena Gomez have segued from separate to together ... at least for the afternoon.

Take a look at this pic. Our Calabasas spies tell us Justin and Selena were just spotted tooling around The Oaks -- where Justin lives -- on their Segways.

The two haven't been spotted together for months, and it seemed Selena was done with him.

Justin is clearly showing her who's boss ... leaving Selena in the dust at a mighty 12 MPH.

Justin Bieber is kicking himself right now ... because ex-girlfriend Selena Gomez and her perfect 21-year-old ass just hit Miami Beach in this bikini.

Beats stripper ass any day of the week.

Selena Gomez is still torn up about her ex, Justin Bieber -- or she's a really good actress ... that's the only explanation for her sappy and tear-filled performance last night in Brooklyn.

Selena started sobbing and weeping near the end of her ballad, "Love Will Remember" -- which is widely believed to be about the Biebs ... partially because the original leaked version of the song featured a voicemail Justin left for Selena.

She also goes into an emotional thank you to her fans, but since turning on the waterworks seems to be her thing -- we gotta ask ...

Here's something Selena should really be crying about -- this awesome moment from "The View" this morning ... when the ladies intro'd her to start singing, and ... well, watch what happens.

Romeo's idea of the perfect 24th birthday gift involves Justin Bieber's on-again/off-again gf Selena Gomez!

What bro code??!!

Justin Bieber hatched his plan to nail Selena Gomez 2 years before they dated -- while she was still dating a Jonas brother -- and TMZ has the footage that proves it.

A 15-year-old Bieber confessed the scheme back in July 2009 -- during an interview with L.A. radio host DJ Skee that was lost in oblivion -- saying his celebrity crush was Selena Gomez ... who was dating Nick Jonas at the time.

Bieber immediately blushes like a schoolgirl and says, "Nobody heard that" -- but less than two years later he attended a Vanity Fair Oscar party with the girl of his dreams.

Selena Gomez is having the BREAST birthday week ever -- and kicked off the celebration by watching a big-hootered lady smash beer cans with her GINORMOUS BOOBS!!!!

Selena -- who turned 21 yesterday -- pre-partied at Beacher's Madhouse theater in L.A. on Saturday night ... where the singer and her crew had VIP seats to watch Busty Heart -- world famous can annihilator.

We're told Selena was sans Justin Bieber for the aluminum massacre ... but he did make an appearance -- in frosting.

Sources tell us ... pictures of Justin and Selena were pasted onto a birthday cake that was decorated in leopard spots ... a dessert clearly inspired by JB's leopard-spotted Audi.

On her way out of the show, Selena appeared sober -- which is good, considering she was still 20 years old at the time.

Now, she's fully legal ... so, cheers!

So much for Selena Gomez being a good influence on Justin Bieber ... TMZ has obtained a photo of the underage singer boozing at a 4th of July party in L.A. -- and Selena just stood by and watched.

The photo was snapped at a Hollywood Hills house -- where the drinking age is still 21 -- and as you can see, Bieber is cradling a beer bottle (Dos Equis to be exact) ... squishing his crotch against Selena.

As we first reported, Selena gave Bieber another shot ... reuniting with him on the condition he clean up his act, and cut the antics -- pot smoking, speeding and bucket peeing -- with his buddies.

Apparently, 20-year-old Selena -- like almost every single college-aged kid -- is still cool with underage drinking though.

As for his taste in brew -- Justin Bieber doesn't always drink beer, but when he does ... he prefers to wear shorts made out of salvaged traffic cones.

Stay thirsty my friends.

Justin Bieber's single days are officially over ... again ... for now ... 'cause he's back on with Selena Gomez -- but TMZ has learned there's one major catch -- he's gotta stop acting like a d-bag.

According to sources, Selena had firmly resisted reuniting with Justin after their most recent breakup because he and his friends have been acting like raging self-entitled jackasses the last few months -- smoking pot, speeding around in expensive cars, and pissing in mop buckets.

But Justin -- being the Casanova that he is -- was able to change her mind ... and on July 4th, we're told he won her back by promising to change his douche ways. Apparently, Selena bought it.

We're told JB and his "Wild Kidz" goons have taken notice of the public backlash against their ridiculous behavior -- hard not to -- and they all decided to clean up their acts.

Sounds like BS -- considering Bieber's abysmal track record for making phony apologies and continuing to act like an oblivious self-important douche-baby -- but our sources say Selena has always been an extremely positive influence on him ... and if anyone can change him, it's her.

Bottom line, it seems like no one else can fix Justin, so why not give Selena a shot? It might just be crazy enough to work.

Biebs Instagrammed this pic today, with the caption "#heartbreaker."

Justin Bieber was straight up BOOED at the Billboard Music Awards last night ... and not like 1 or 2 people ... it was a straight up CHORUS of boos ... and it made Justin super uncomfortable.

It all went down when Cee Lo called on Bieber to receive the first ever Milestone Award -- but when Bieb got to the stage, the crowd turned on him.

Of course, there were some screams from the hardcore Bieber fans ... and JB managed to silence the haters for a minute by thanking Jesus Christ (who's gonna boo JC?) ... but overall, more boos than a haunted house.

As for the Bieber/Selena Gomez situation, the two were NOT seated together during the show -- despite a pre-show photo of the seating arrangement that suggested they would be.

Instead, she was kickin' it with Taylor Swift ... and didn't stand when Bieber's name was called for the Top Male Artist Award.

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.

Justin Bieber let his fans know he's back with Selena Gomez -- but only for a few moments -- as he posted a pic of himself getting cozy with SG ... and then quickly deleted it.

Gomez sparked reunion rumors when she jetted off to Norway to meet up with JB, who is touring there.

As we previously reported ... Selena and Justin have seen each other periodically since breaking up at the end of 2012. We're told he's been "tortured" because she's been giving him mixed signals.

Posting a pic for the world to see and then deleting could qualify as a "mixed signal."

Justin Bieber is not over Selena Gomez ... in fact, she's still very much in the palm of his hand.

We started looking closely at pics of Justin ... and we came across this one (left) of Justin leaving a museum in Amsterdam, and his sorta ex-GF was along for the ride ... as the screensaver on his iPhone.

Justin's background image of choice is clearly a pic of Selena. The sultry pic is from a March 4 photo shoot, TMZ has learned.

Only question is ... did she send it to him, or was he keeping tabs on her?

As TMZ reported yesterday, she flew into Oslo, Norway, to hook up with her on-again, off-again BF.

Now it's clear ... their continuing obsession is DEFINITELY mutual.

Selena Gomez has landed in Norway ... and sources tell us she's on a mission ... to hook up with Justin Bieber.

Selena was spotted getting off a plane at the airport in Oslo ... just about the time JB was getting ready to hit the stage.

Beliebers -- who obviously know where Justin is at all times -- have been buzzing about a possible rendezvous ever since a Norwegian pop star tweeted about seeing Selena on the flight from L.A. to Oslo.

Sources connected with JB tell TMZ ... it's no coincidence they're in the same country at the same time.

As we previously reported ... Selena and Justin have seen each other periodically since breaking up at the end of 2012. We're told he's been "tortured" because she's been giving him mixed signals.

So much for never ever ever getting back together. Selena, Taylor ... same thing.

Just in case you needed further proof why Justin Bieber is a fool ... here's Selena Gomez at the MTV Movie Awards.

Her new song is called "Come and Get It."

BUSTED!!! Justin Bieber's freeloading friend is NOT hooking up with Selena Gomez, even though he went to Herculean lengths to make it seem that way ... and we have video proof.

King Kevi -- who became famous-adjacent recently by living in Justin's house and throwing ragers with lots of girls, bongs and beer -- caused a stir when these pics (below) surfaced, showing the fake royalty appearing to leave Selena's San Fernando Valley estate Saturday night.

Various media reported Kevi -- the up-and-coming nobody -- was inside her house and "hung out." But we got our hands on surveillance footage taken the night in question ... showing Kevi posing in front of Selena's house while camera flashes went off ... but never making it past the gate.

Selena wasn't even home at the time the photos were taken.

In other words ... it was all a setup by the guy who is mooching off the Biebs.

He's no Kato Kaelin.

2:45 PM PT -- King Kevi tells TMZ the whole thing is a simple misunderstanding -- saying, "I was there to drop off something to a friend at the party. I walked multiple times to the front gate to try to call my friend and every time I had to chase off the photog."

He adds, "After the last attempt, I went to my car to leave and that's when my friend called me to come inside. When I backed in, I gave him another call to open the gate and he didn't pick up so I left because I saw the photog come back around."