"Godwin's Law (also known as Godwin's Rule of Nazi Analogies) is an adage formulated by Mike Godwin in 1990. "
The law states: "As a Usenet discussion grows longer, the probability of a comparison involving Nazis or Hitler approaches one."
"Godwin's Law is often cited in online discussions as a caution against the use of inflammatory rhetoric or exaggerated comparisons, and is often conflated with fallacious arguments of the reductio ad Hitlerum form."
Often in the gun ownership debate gun control advocates rapidly descend to invoking Hitler or the Nazi's. To me this has always signaled winning the debate. The Hitler card is usually played when logic won't help, or worse, when logic is against them.
--I find it also very amusing when they invoke Hitler but most don't know that Hitler and the Nazi's were huge gun control advocates.