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!
when you kick someone's door in and rob their house. the reason for it being named "hiyah" is because it resembles a powerful karate kick(doesn't have to be a karate kick, just strong enough to open the door)which you would yell "hiyah"..you don't yell it though, unless you want them to know you are trying to rob them.
steve:"aye man, you aint down to hiyah that nigga's house down the street with me later on tonight."
terry:"hell yeah im down, i heard that nigga was hella rich. ima see if i can get a free ps3."