At the stroke of midnight (or 6am, as it were), Kourtney Kardashian turns back into a mommy, even after a night on the town with Justin Bieber!

Kourt never skips a beat and her kids are always her priority but when duty calls (or Bieber booty calls), she slips into her nipple-exposing lace bodysuit, throws on a jacket and scoots right over to the club to meet up with her 22-year-old boy toy! But when morning comes, she's back in Calabasas, standing in her kitchen, wrapped in her organic cotton robe, preparing cereal with almond milk for her three kids.

Tuesday we spotted Kourtney taking Mason to a music class looking like a total rock star in a Wu-Tang tee, biker jacket and booties. I mean, if Bieber's gonna go for an older woman, why not Kourtney?!