I prefer the one that goes there was a philisophers convention, but the manager was a room short and had to tell Aristotle he had no room.
No Worries says Aristotle who heads down to Descartes room. He knocks on his door and tells him he has to leave because there are no more rooms and Descartes is in the wrong room.
"I think not!" Descartes cries, and promptly vanishes, leaving Aristotle to take his room