A nun is driving the convent's car through some very lonely countryside. The car stops and she notices there is no gasl left in the tank. So she walks to the nearest gas station.

Being a nun and a little unworldly, she forgets to take along the can. The nice man at the filling station has no can either, so he hands her a chamber pot full of gas.

The nun walks back to her car and starts pouring the gas into the tank. A bypassing car stops, and the driver looks out at the nun and says:
"Sister, I wish I had your faith."