What does FK stand for?

Flash Kick

The "Flash Kick" is an iconic special move originating from the Street Fighter series, most famously associated with characters like Guile and Charlie Nash. It's a powerful, often anti-air, attack where the character quickly kicks upwards, often accompanied by a visual "flash" effect. In many fighting games, this move is performed with a "charge input," meaning the player has to hold a down or down-back direction for a short period before quickly inputting an up direction and a kick button. This makes it a distinctive and challenging move to master, crucial for defensive play and punishing airborne opponents. The term "Flash Kick" has become so ingrained in fighting game vocabulary that it's often used to describe similar "down-up" charge kick moves in other games as well.