An Englishman, a Scotsman and an Irishman are driving through the desert when their car breaks down. So they have to get out.

The Englishman takes a bottle of wine with him, the Scotsman takes an umbrella and the Irishman takes a car door.

On the way they meet this old bastard. He says to the Englishman "I know why you've got the wine so you can have a drink when your thirsty", He says to the Scotsman "I know why you've got the umbrella to keep the sun off you", "but" he says to the Irishman "Why have you got the car door?" and the Irishman replies "If I get hot I can wind the window down!"