Please...enlighten all of us idiots, Buddha! Or maybe you'd rather keep posting 3 or 4 word replies that signify nothing but sarcasm.
Ok, check it out, i'll do this for you, just this once.
A flash knockout is a knockout where the recipient may lose consciousness, however it is very brief and the fighter may still have the wherewithal to begin to defend themselves very quickly after they have been "knocked out". Flash knockouts may exhibit many of the signs of a 'traditional knockout': the head may bounce off the canvas, the eyes might roll, but generally speaking, there is still enough composure for the person who has been rocked to make the argument that they are still in the fight. This is either done by continuing to fight (obviously) or by arguing with the ref after they have stopped it (See josh koscheck vs paulo thiago). It's a strange grey area, in boxing, its not a problem, because if you get dropped, but recover uber quick, just stand back up and get your count. Where the problem lies in MMA is that the ref has to make a split second decision when he sees a fighter in a compromising position. That's why you will constantly see lots fighters protesting early stoppages, the fighter never feels as if they have suffered a complete knockout defeat, that have retained the necessary composition of consciousness to continue competing. On the other hand you have the referee who has seen all the tell tale signs of a body beginning to go limp, ready to take unnecessary damage, they do their job, stop the fight, airing on the side of caution, but it looks really bad when the fighter spring right up to their feet, seemingly miraculously recovered once the bout has been called.
It is a tricky area, and in honesty, can be pretty difficult to define and pin point.
I see a lot of the confusion in this thread from the pure fact that this topic was even brought up. Favorite flash KO's is a strange topic for discussion and flash ko's are incredibly unsavory for everyone involved. The loser of the fight feels like they were robbed of an opportunity to recover and keep fighting, the winner feels like the nature of their victory is now debatable, the referee could be chastised for an early stoppage, the the fans may feel like they didn't get a definitive answer.
TL;DR: A flash knockout is the result of a strike where the "knocked out" opponent displays a much shorter transient period of lost consciousness, usually followed by a quick recovery period.