90% of Americans believe at least one conspiracy theory

Oh no you don't. Mark Twain is the pen name of a real character.

Down in town at our court house there's a place where he once sat. I've sat in that same place.

I don't know where he sat, so I solved that problem by my sitting down everywhere one could have sat.

I've sat where he sat.
I dunno how to break it to you, but Mark Twain is simply a character created by possibly the greatest American author, Huckleberry Finn