An ellision of "feet" and "attack." A sport where to competitors put their hands behind their backs and kick at each other below the waste. Different variations include:
Last Man Standing: The two fackers kick at each other until one facker can no longer stand. The last facker still able to stand wins.
Classic: Fack in rounds, sort of like boxing.
Fackarate: Kicking your opponent in different places scores different amounts of points. The facker with the most points at the end of the round wins the round. Best of 5 rounds.
In order to fack, you must have strong legs, ability to withstand pain, and, most importantly, a ferocious kick.