Descartes and Heisenberg walk into a bar and order drinks. After they empty their glasses, the bartender comes over and asks them if they would like another round. Descartes ponders this for a moment and replies 'I think not' — then POOF! disappears.
The bartender, obviously shocked, turns to Heisenberg and says 'Did you see that???'
Heisenberg pauses to consider, then replies 'I'm uncertain.'
[Via Kevin Schofield.]
what?