Well, I can only comment on the ones I was invloved in.
The discussion about McDonalds can be traced back to an assertion that I took issue with. Something about capitalism being based upon quality and merit while socialism encouraged dependancy. Before that, the discussion was to the effect that socialism was un-American and should not be foisted upon a capitalist society without its consent.
The argument over the Ten Commandments and my alleged desire to reclaim the 13 colonies for the British Empire can be traced back to a protest against Obama's claim that the Constitution was fundamentally flawed.
Both, I think, were relevant to the original question and hae helped it move on.