Found this by chance.

If you try to go to a page in RPS that doesn't exist, you get a "Guru Meditation" error. What is that you ask? That is a reference to an old variant of the BSOD in a retro PC known as the Amiga (it was a separate platform - not a dos pc).

What I have now found is the origin of the origin :) If you are an Amiga user and wondered what the phrase meant, here is your answer.

http://www.amigahistory.co.uk/joyboard.html
(scroll to the bottom)