Here's a long one I got off a philosophy professor in class the other day:
A well-to-do widow arrived at Logan Airport early for a flight to Midway in Chicago with her sole companion, Wesley, her cat. Told (to her chagrin) that she couldn't bring a cat onboard the plane, they produced a cardboard box, and repeatedly assured the woman that no harm would come to her cat. Over her protestations, and with their repeated affirmations that no harm would come to the cat they made he, r put the cat in the box. Well, everything's good at that point, it's a great flight, clear skies. everythings hunky dory.
Then they land.
Imagine the horror of the grounds crew when, after being radioed that a possibly crazy woman had a beloved cat that was to come to no harm whatsoever, they open the box and find one very dead cat.
So the grounds crew does the only sensible thing: order the flight crew to let nobody off the aircraft, especially not the overdressed elderly woman, and tear off to the nearest animal shelter to find a decent replacement. After frantically haranguing the staffers at the shelter, they come away with a cat that matches the deceased almost perfectly. Holding the dead cat up to the live one, nobody can distinguish twixt the two. So, live cat in hand, dead cat in the garbage, they rush back to the airport, new cat goes in the box, radio the flight crew to let the increasingly angry passengers go, and the day is saved. So the lady finally disembarks, and the grounds crew finds her (hiding their breathlessness) and opens the box for her. She checks the box, and gives a confused glance to the head crewman. "That's not my cat". Stunned, exchanging incredulous looks, the grounds crew insist, "No, lady, that's the cat, look, the box's got your name on it, that's the cat from Logan". But the widow again shakes her head, confused. "No, no, no, that isn't my Wesley." The crew is crestfallen. All that work for nothing. Finally, one of the crew asks, "What makes you say that? How'd another cat get in the box?"
The woman shrugged. "I don't know. But my cat's dead."