A Vrook is anyone who is unable to see the ICP Raiders. A Vrook should be shot (although shooting the Vrook won't kill it) upon coming into contact with you, and if not, you yourself may become a Vrook, which is worse than death itself. The only way for a Vrook to die is by a Jedi killing one, which can be rare because the Jedis were wiped out in the latest Jedi Civil War.
"You cum-ass-fucking-shit-bitch-whore, get the fuck away from that Vrook. He's even more of a ho ass shit fuck than you. Now it's time for my Jedi Mind Trick to own that bitch."