Scotsman [me] irishman and american...?

a scotsman , irishman and american were walking through the desert gagging for a drink, scotsman finds a lamp, gives it a rub and a genie pops out, he says since there are three of you ill give you 1 wish each,, scotsman says i wish for a gallon of scotch to quench my thirst going through the desert, the irishman says ill have a gallon of guinness to quench my thirst, the american says ill have a car door please, so away they go with their wishes and the genie says to the american , why did you wish for a car door? the american says so i can roll the window down its bloody roasting here.