look up any word, like dog in the bathtub:
 
2.
A sound effect in a First Person Shooter called Half-Life 2, made by a rebel, indicating that a Manhack is near by.

Popurarly used in "Gmod idiot box", a machinima series by DasBoSchitt. Shouted by "Dr. Hax", a big head copy of Dr. Breen(one of Half-Life 2 charachters), which is looking for people using cheats.

There is also a downloadable weapon made for game Garry's Mod which makes you shout "HAAX!!!" and shoot a monitor at the enemy you're pointing at.
Example 1:

A lot of Manhacks flying at the group
-Haacks!!!-One of rebels shout.

Example 2:
Chuckles the Cheat is using cheats on Counter-Strike
"Yeah!" Chuckles says.
"HAAX!!!" Pointing at Chuckles says Dr. Hax. A monitor flies at Chukles.
by GModPlayer April 24, 2010
 
1.
The word HAAX is somewhat different to the word hax in the sense that it is not the original word. Instead, it originated from a man known as 'doctor HAAX' inside of a series on YouTube called 'The Gmod Idiot Box'. Doctor HAAX, after realising that someone called Chuckles is cheating at a LAN party, proceeds to scream , "HAAX!" and a computer monitor is thrown at Chuckles's head. He proceeds to do so through the YouTube series.
Doctor HAAX: HAAX!

*Monitor collides with face, producing bloody mess*
by Floatypineapple June 10, 2009