A blonde, a brunette, and a redhead enter the desert.

A blonde, a brunette, and a redhead enter a desert. They are each allowed to bring one item with them on their journey. Knowing that the desert is very hot and dry, the brunette bring a large jug of water. The redhead, seeing that the brunette had lots of water, brought a large cooler. The blonde, however, inexplicably brings a car door. Once they are inside the desert, they attempt to work out what they have brought. The brunette says, I brought water to drink, and the redhead brought us a cooler to keep it cold, but why did the blonde bring a car door. The blonde responds, so if it gets hot, I can just roll the window down.