Ive only seen it a few times but it was a great ko. I wanna say it's over 10 years old or more. Basically the gif is of a dude hitting a lead leg kick -> lead body kick -> lead high kick combo for the ko. The guy who landed the combo was a white guy with medium shaggy hair I think. I dont remember if it was a ufc fight or not. Sorry not more details I'm going off memory.