Verb (most commonly), Noun, Adjective. It basically means horrible horrible luck and anything generally associated with it. Named for Koji for the digitalmzx.net forums who seems to have such a horrible run of bad luck that he must've broken a funhouse, not just a mirror.
v: "Yeah, I got zapped by lightning walking home from school on a clear day" "Wow, you got kojied."
n: "A shovel fell out of a plane onto my head" "Thats koji for you."
a: "I got trampeled by a rampaging herd of Indian elephants while walking 10 miles from the zoo." "Sounds like a koji day."