This joke was shared to me by the informant during the course of a conversation. She told me the also that she had heard this joke from one of her friends as well.
“So Rene Descartes walks into a restaurant and sits down at a table. The waiter comes up to him and gives him the specials for the day. The waiter says to him “We have a great linguine with cream sauce, tomatoes, and clams. Would you like to order it?’ Rene Descartes rubs his chin and says ‘I think Not’ and then promptly disappears.
This joke seems to me to be an ‘inside joke’, that is, one only really gets the joke if they have already know who Rene Descartes is. However, the joke relies on Descartes famous phrase ‘I think therefore I am’, implying that his indecisiveness has now led to the termination of his existence. A joke such as this would most likely shared by someone who has friends who study philosophy or were familiar with it. However, it may still have an effect on someone casually familiar with Descartes.