Came from the stoner underworld. When one of your comrades is staring into space and you want to ask him, 'What are you thinking about/What was teh last thought which went through your mind?', save time (and don't let them forget) by using this word instead.
(Friend staring into space)
- 'Doh. I was just thinking about how, because our fastest possible reaction time is 1/30s, we're therefore always living in the past, and then maybe this is all a flashback and I'm actually already dead twenty years in the future.'