Kourtney Kardashian spent part of her weekend celebrating sons Reign and Mason Disick’s birthdays. On Monday Mason turns six and baby brother Reign turns one.

An “outer space” and “alien” theme was evident, and the grownups appeared to have as much fun as the children.

“Alien laser tag,” Kourtney Kardashian captioned this shot she shared on Instagram.

A photo posted by Kourtney Kardashian (@kourtneykardash) on Dec 12, 2015 at 7:39pm PST

The birthday party took place at Kourtney Kardashian’s home.

“UFO sighting ?” she captioned this photo.

A photo posted by Kourtney Kardashian (@kourtneykardash) on Dec 12, 2015 at 8:38pm PST

On Friday night, Kourtney Kardashian was spotted hanging out with Justin Bieber. Hours later–at about 4 a.m., she was seen leaving The Montage–the hotel where the “Where R U Now” singer often stays. This has fueled rumors there’s something going on between Kourtney Kardashian and Justin Bieber, but he has long been a close friend of the entire family.

Report: #JustinBieber has been "casually hooking up" with #KourtneyKardashian https://t.co/Kr6DWqnXDG pic.twitter.com/Q2sUPKecI7

— ET Canada (@ETCanada) December 13, 2015

There’s been no word on whether or not Scott Disick joined Kourtney Kardashian and the Keeping Up With the Kardashians gang for Mason and Reign’s birthday bash. The two have been getting along well since he spent time in rehab, but sources say they’re not getting back together.

Might Kourtney Kardashian have a rebound relationship with Justin Bieber or do you expect that’s nothing more than a rumor?