Justin Bieber may be juggling sisters, because he partied Tuesday night with Kendall Jenner at the same night club where he hooked up with Kourtney Kardashian over the weekend.

Justin and Kendall arrived separately at The Nice Guy in WeHo at around the same time -- 10 PM.

They left separately, too ... just like Friday night when Justin and Kourtney left Justin's go-to club and headed for his Bev Hills hotel, where she stayed 'till 4 AM.

8:46 AM

Tyga and Kylie Jenner are together even though they act like they're apart -- not exactly the way the real world works ... but their world's a whole other thing. 

As we've been reporting, our Kardashian sources say they've made a deal which was mostly Kylie's doing ... that they each give each other space professionally, so it doesn't mess up their respective brands.

That's why they showed up separately at the 2nd Annual Diamond Ball Thursday night at the Santa Monica Airport. 

Rihanna threw the ball and it sounds like Kylie's taking a page from RiRi's playbook.

5:23 AM

Justin Bieber may be juggling sisters, because he partied Tuesday night with Kendall Jenner at the same night club where he hooked up with Kourtney Kardashian over the weekend.

Justin and Kendall arrived separately at The Nice Guy in WeHo at around the same time -- 10 PM.

They left separately, too ... just like Friday night when Justin and Kourtney left Justin's go-to club and headed for his Bev Hills hotel, where she stayed 'till 4 AM.

3:32 AM

Daphne Joy -- best know for this, and being 50 Cent's baby mama -- is a sight to behold from almost every angle you can imagine ... but especially from behind.

Daphne's got a 3-year-old kid with 50 Cent and is rumored to be dating Jason Derulo now. She pretty much gave away the secret to her dating success on the beach in Miami.

Fiddy must love watching her leave.

7:08 AM

She was late .... for a very important date -- so claims a Vegas nightclub which is suing for a refund on the $236,000 it paid Nicki Minaj after she allegedly botched a club appearance after the Mayweather vs. Pacquiao fight. 

According to the lawsuit, Nicki was booked to appear at Chateau Nightclub in the Paris hotel at 12:00 AM sharp after the May 2nd fight ... stay for an hour ... and perform 2 songs. 

Problem is ... people behind the event claim Minaj didn't show up until 1:19 AM and only stayed for 34 minutes. They're pissed -- because they allegedly pre-paid Nicki's people.

The party people say the clubgoers were equally pissed -- and it affected their ability to sell VIP tables at the club that night, which were expected to fetch in excess of $25,000 each.

Nicki isn't named a defendant in the lawsuit -- but her booking company is, Pink Personality, LLC.

We reached out to Nicki's camp for comment --  so far, no word back.

11:47 AM