Comes from "cacat" which means shit in Romanian.
It's often used to insult someone, or sometimes is used to show a current statement of something.
It's used mainly on internet chats.
Though it's used 90 percent in the above cases, some freaks use it to show that they are pissed off on wife, children, counter-strike, world of warcraft account, aliens etc.
Mai mananci kkt de caine ? (insult)
Ai de capu' meu, esti in kkt frate! (state of something)