King Ghidora: "Dumbest rumor ever was that 9/11 was an inside job and that all Jews knew about it ahead of time and weren't in the building. Also part of the same rumor was that the Pentagon wasn't hit with a plane but it was hit by a missle instead. And it was all a pretense for W to annex the middle east for the oil."
That one isn't related to a gun ban. But I am with you. I tolerate a lot of silly conspiracy theory talk around me, because I know that some of it has a kernel of truth to it and some very interesting things may be learned in such discussions, often having nothing whatever to do with the alleged conspiracy.
But I draw the line at the "911 Truthers."
Whenever someone starts that crap, I hold up my hand, and tell them that before I listen to another word of it, they're going to have to hear about the wonderful colleague and friend and secret crush whose flight diverted to the Pentagon right over my head. Hundreds of thousands of people were involved, immediately present or directly observed the events of 9/11/01, and all claims by the so-called "Truthers" are ridiculous and easily debunked.