Kourtney Kardashian Frowny Faced Scott Disick Front and Center for BD Bash

4/19/2015 8:32 AM PDT

Kourtney Kardashian -- Frowny Faced Scott Disick Front and Center for Birthday Bash (PHOTOS)

Kourtney Kardashian celebrated her 36 birthday Saturday night in Vegas with boyfriend Scott Disick ... and he looks less than enthused.

The bash was thrown at 1OAK.  There was a pretty big crowd, sans all the other Kardashians.  Kim's at home in L.A., Kylie's at Coachella with Tyga and Kendall.

Khloe was busy Saturday night throwing a shindig for her new group messaging app called Regroupd.

There was a buzz that Rob Kardashian might have gone to Coachella as well, but there's no evidence of it.