Hiyah!! is a word that is awesome and I am severely dissapointed it hasn't been defined yet. It is the noise that can be found in many of the Bruce Lee movies, Chuck Norris movies, and for some reason, lots of hollywood comedies. Hollywood uses it as special affect to add character to when Chuck is beating the living daylights out of the bad guys.
Did you see walker texas ranger yesterday? Chuck kicked the badden in fifty bajillion different dimensions! And he screamed "Hiyah!!" as he did so!