For their hike to town, they each decide to take one thing with them.
One man takes a jug of water.
The second man takes a sandwich.
The last man takes one of the car doors.
The first man says to the last man: "I'm bringing the water because if I get thirsty, I can take a drink. And it makes sense to bring a sandwich in case we get hungry, but why bring a car door?"
The last man replies
Spoiler: