Kourtney Kardashian & French Montana Party In LA After 'Twerking' & Upsetting Khloe

Kourtney Kardashian and her sister Khloe's former flame French Montana are still pretty cool despite their breakup.

The two arrived together at Genghis Cohen in Los Angeles to celebrate the birthday of a mutual friend Steph Steph.

After about two hours there, they moved on to Hyde Clyde to party some more forStephanie Ann Shepard's birthday, ending their night at 2:30 a.m.

As readers know, this wouldn't be the first time they were spotted partying together. On the night of P.Diddy's 49th birthday bash in West Hollywood, RadarOnline.com exclusively learned the two were "all over each other."

“Kourtney and French were on each other,” a source who attended the party at Ysabel in revealed at the time. “She was twerking on him, he had his hand on her waist and a** and was whispering in her ear all night.”

Then Khloe reportedly caught the two in action and she "lost it!"

“Khloe went in, telling Kourtney she was out of line, disrespectful, and desperate,” a source close to Khloe told RadarOnline.com. “Khloe was beyond hurt. She felt utterly betrayed and was ashamed of Kourt and couldn’t stop screaming.”

The sisters allegedly didn't speak for some time afterwards as Khloe believed her sister “should have known better” and “not hit on her exes.”

As readers know, Khloe, 35, and French ,34 dated on and off amid her separation from former NBA player Lamar Odom, 39.

The "Don't Stop" rapper detailed his relationship with his ex Khloe in an interview with Haute Living.

“Me and Khloé are always going to be friends,” he shared. I feel like we had a real dope relationship―there was no bad blood, nobody did something to somebody that we couldn’t come back from.”