actually is "Quad Erat Demonstrandum" and it does mean "which was demonstrated".
Comes at the end of a mathematical proof, usually.
Maddox uses it best.
Pirate: "I claim that illegal immigrants should be paid the same wage as americans, you claim you dont want any 'spics, gooks, nips, russians' and lets not forget 'sand niggers' to 'take our jobs for less money' because they 'dont belong here'. Also you said i could 'like your
Pirate: "Wooo WOOO. Here comes the clue train, last stop is you! Now if companies like Wal-Mart are forced to pay the same wage to illegal immigrants, then any incentives these companies would have had to hire illegal immigrants if effectively destroyed."
KKK member: "Ah, i see. Will you still lick my balls?"