It's an abbrevation for "Kiri Irooni Guy." Kiri Irooni Guy is Persian phrase referring to an immigrant from Iran who tries to hard to fit into his adoptive country and goes to some extreme lengths to fit in (grow his hair to 6 inches or longer then spike it, trim his chest hair, wear tight knock-off Diesel jeans, wear fake aligator shoes, etc.)
Like OMG, did you see that kig? What a loooooooooooser!!!