Does "I would totally fuck myself. Anyone who wouldn't has self-esteem issues" refer to someone else fucking themselves or everyone else who isn't Derren Brown fucking Derren Brown?

Hmmm, excellent point. I suppose, given the 'self-esteem issues', that it depends on whether everyone in the world is in fact secretly and/or unknowingly Derren Brown, which is not entirely implausible.

I don't like walking under signs in case they fall on my head.

You see, that's actually semi-rational. I just have completely out-of-nowhere impossible superstitions.