Miranda Kerr & Kourtney Kardashian: First Order of MILFs Now in Session

Miranda Kerr, Kourtney Kardashian, and Lily Aldridge convened the coolest/hottest version of a PTA meeting, and they did it ... in a bathroom.

Kourt, her supermodel friends and Paul Mitchell honcho Michaeline DeJoria all hung out somewhere in L.A. Thursday night for what they all deemed "Girls night" -- which apparently means ... selfies in the ladies' room!

Hmm ... think Justin Bieber's ears were ringing at all last night?