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."
It is said of the situation where a person has the bad luck to make contact with his testicles against an undefined surface or object, intentioned or not.
Given the nature of the word, it is more appropriate to design cases where the interaction is made with a moving object, for example, a ball.
Although it is extremely painful for the victim, it tends to be considerably funny to people who witness it.
Today in the baseball game the pitcher took a nutshot; the baseball hit him in the nuts.
Man, I just watched the funniest nutshot video ever.