Fighting games generally go out of their way to flash a great big K.O. across the screen when the round ends, so players know their fighter is still alive and coming back for another round.
But Mortal Kombat changed all that, because the "mortal" in the title meant characters were often dead by the end of the round, and could be dispatched with a grisly Fatality finishing move.
So how the hell did a fighter who was beaten to death come back for more in the next round? (Barely NSFW due to language)
This Dorkly video poses a theory, although it still doesn't explain how they come back from a spine ripping fatality.
-Via Laughing Squid