1. phrase used to reply to a person, of inferior mental capacity, when he/she talks shit about things he has no fucking clue about (usually used to quickly end an argument with one who knows fuck all!)
Used at international political conferences when replying to idiotic world leaders' statements (e.g. George W. Bush), to those that dispute war crimes (e.g. the Jewish holocaust, Armenian genocide, etc.), or those who dispute historical truths (e.g. the Ancient Egyptians built the pyramids, Alexander the Great was hellene, Hitler was a monster, etc.) When any of these statements are made, intelligent folks reply to the Cretin with "Buy a Clue!"