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When one interrupts a 2 person comment chain on a Facebook status update, picture, etc. Typically, the original commenters will start a nice, engaging conversation, and then the "blocker" will barge in with a totally unrelated comment, thus disturbing the flow, and consequently delaying your chances of scoring with the hot chick that's totally interested in what you're doing for the weekend...
-Dude, why are you facebook cock blocking?

-Sorry man, if I knew you were trying to bone that chick, I wouldn't have made that fart joke.
by Sweatshop February 16, 2010