The act of blowing off a friend or acquaintance, When someone creates a believable scenario of intentions to meet up and fails to, or purposely declines to show up, Standing someone up, or the means of severing a social connection like a friendship.
Person1: gee, hav'nt heard from dexter in like two weeks... think he's dead?
Person2: Not sure, he always flakes out on you unless you agree to meet up on his terms.
Person1: hey man, wanna go get schwasted tonight?
Person2: yeah, I was supposed to meet up with that creepy guy later, but i'll just be flaking out on him, now won't I?
Going out for a drinking session with friends and 'Roy' Flakes Out, by opting to stop drinking and go home early. This person would then be referred to as: Flaking out, Flaker, Corny, Flaked Out, Flakey.