If you mean the long, "AAAAAAGGGGHHHHHH!!!", I always thought that sounded like dying Klingons. Which I thought appropriate when timed right when I destroyed a Klingon ship.
No it's more like someone yelling Yah! during the fight music, like some overexcited idiot caught by accident on tape while recording. It's also a type of "sampling" used in hip hop music. The artist believes this changes the music enough to call his own while adding what he thinks is flair.