It seems that the subject of this thread has been creeping into common discourse. So I'm bumping it.
An invisible pink unicorn type idea is presented about 15 minutes in:
He argues that religious ideas are basically very human concepts with a little twist. He discusses 'minimally counter-intuitive worlds' where humans might be inclined to believe in a super-intelligent being that created the universe, but not in an invisible pink unicorn (though he talks about a tree that can hear prayers under certain conditions, versus a tree that sits your exams, eats spaghetti and parks your car for you).
Which is possibly one reason why people dismiss IPU type ideas as 'clearly ridiculous'...the IPU is maximally counter-intuitive rather than minimally so.
Edited by Modulous, : No reason given.