Someone who is noncommittal or agrees to everything but then never shows up and therein flaky. So flaky to the point of being almost professional in the practice of it. A professional flaky person. Hence, flake-up artist.
e.g.
Ben: "Liv! We haven't met up in ages!! Fancy meeting up this weekend? I'll be in your neck of the woods any how so we should deffo meet up for a crafty drink! You down?"
Liv: OMG! Ben!!! YES. We gotta do this! Bell me when your here and I'll come down!
(24 Hours passes and Ben arrives at agreed location)
Ben: "Hey Liv, I've just arrived! Where abouts are you?
A contraction of "flare-up" and "flaming" (as in homosexual). Briefly becoming very attracted to the same sex, perhaps only while under the influence of drugs or alcohol. In other words, a straight person having a gay moment, or a gay person having an EXTRA-gay moment.
Girl A: "I thought Emma was here with Dave."
Girl B: "She is."
Girl A: "Then why is her tongue down Megan's throat?"
Girl B: "Oops - looks like another flame-up. She had one of those at last year's sorority mixer."
Someone who jumps from one relationship immediately into another one.
Serial monogamists can not stand to be alone and often suffer from vast commitment and insecurity issues.
Because they jump into relationships immediately after the previous one has ended, serial monogamists typically don't take the time to reflect on their behavior or why their previous relationships failed; thus, they end up making the same relationship mistakes over and over again.
Person 1: Damn, Dustin already has a new girlfriend?! It's only been two weeks since he broke up with his fiance! I think he's a sociopath.