One day an American, and Canadian and a Polock go for a trip in the desert.

After they are walking for a while they start talking and the American says, "I brought food so we'll have something to eat when we're hungry."

The Canadian says, "I brought water so when we get thirsty we'll have something to eat."

The Polock says, "I just brought a car door."

The first two men look at each other puzzled and ask him, "Why did you bring a car door."

The Polock says, "So we can roll down the window when we get hot."