That's funny, but then it's not actually true, is it. The ultimate cause of farting is a microbiological process that mainly involves methanogens, I think. No one ever claims that by farting they are going to be able to create new subatomic particles or examine conditions close to those that existed at the start of the universe . So no, I don't see how there is even a theoretical risk of Doomsday associated with that particular sort of Big Bang (pardon the pun).

Just to clear things up, I didn't ask because I am fretting about it, but because I wanted to know whether or not the theoretical risk existed, or whether it was just urban myth. By 'theoretical', I mean a non-zero risk consistent with current theoretical understanding.

And you say yes, there is. So that clears that up, I think.