You can't actually eat the world's hottest ones. They are collector sauces that are literally too hot to be safe to eat, as in they cause burns. Dave's insanity is one of the extreme ones that are till safe, and there's another popular line that I can't quite remember the name of, but has the word death in it. Their collector bottles feature wax tops with skulls.
Mo Hotta Mo betta would be a good source. Brain is not working at all this morning. I know there's another mail order source I used to use and can't remember it!
do some googleing