Here goes:
Godwin's Law (also known as Godwin's Rule of Nazi Analogies) is an early principle of Internet dialog or it damn well should be. This sanguine postulation was formulated by Mike Godwin in 1990. The law makes the trenchant observation that "as an online discussion grows longer, the probability of a comparison involving Nazis, Fascists or Hitler approaches one."
Or to state it less mathematically: some lame ass who can't really think for himself is going to call the other guy a Nazi or a Fascist or even Adolf himself. Sooner or later as the discussion heats up and the flaming begins, someone will pull out this universally overused analogy. Generally the user cannot spell analogy nor pronounce fascist.
Godwin's Law does not dispute whether, in a particular instance, a reference or comparison to Hitler or the Nazis might be apt. It is precisely because such a reference or comparison may sometimes be appropriate, Godwin has argued, that overuse of the Hitler/Nazi comparison should be avoided, as it robs the valid comparisons of their impact.
Although in one of its early forms Godwin's Law referred specifically to Usenet newsgroup discussions, the law is now applied to any threaded online discussion, electronic mailing lists, message boards, chat rooms and more recently blog comment talk pages. To this I would add any and all group discussions particularly one that involves the potential consumption of large amounts of wine. [Oops, did I give too much away there. Will they know I am writing about them?]