An acronym for Cock-Fucking-Road-Block. A derivative of cockblock. Its meaning is a ridiculously large obstacle placed in the way of a male getting some. Its etymology is based on the English colloquialism cockblock but is intensified by both the addition of the word "road" which suggests a larger obstacle and "fucking" which is of course a general intensifier in most modern vernacular.
Brian's invitation of his mom to the party served to be a CFRB for John but only made Steve's evening better.