Happy birthday, Kourtney K!

The mother-of-three celebrated her 36th birthday in Vegas last night at 1Oak, with hubby Scott Disick (sober, we hope) by her side.

The reality star looks stunning in a short, little black dress, showing off her amazing post-baby bod after giving birth to baby Reign in December.

Meanwhile, Scott didn't look quite so amazing. The newly-rehabed bad boy looked a little bored as he sipped water from the VIP table, according to sources. Kourtney made sure Scott stayed close -- probably wanted to keep an eye on him. And apparently the night went off without a hitch. This time ...