James Harden and Lamar Odom -- Eskimo Brothers Convention at Meek Mill Show

The inaugural "Hell Yes, I Banged Khloe Kardashian Conference" went down in Las Vegas ... when James Harden and Lamar Odom popped up at a Meek Mill concert.

Harden and Odom -- Khloe's current boo and estranged husband -- were both in the crowd at Drai's Nightclub Saturday night for Meek's show ... and luckily, Khloe was NOT with her guy at the time.

The hoops stars never compared notes -- about basketball, and ONLY basketball -- since they reportedly kept their distance on opposite sides of VIP ... during the 'HYIBKKC.'

Harden and Khloe have been spending quite a bit of time together lately -- they took a spin class together last week in Los Angeles after spending July 4th weekend together in Vegas.

Of course, Khloe's still married to Lamar -- but she's been spending all her free time with The Beard lately ... and Harden too.