Three guys are walking in the desert. After they are walking for a while they start talking and taking inventory of their supplies.
The first man says that he brought a sandwich, so if they get hungry they will have something to eat.
The second man says that he brought water, so they can stay hydrated on their journey.
The third man says that he brought a car door.
The first two men look at each other puzzled and ask him, “Why did you bring a car door?”
The third man says, “So we can roll down the window when we get hot.”