Carrying an empty 5 gallon gas can up to someone who is already pumping gas and asking them to add a little to your can after giving them a sob story of how your money got stolen at the last gas station. Sending a girl to do this job will get you a full can, but guys are not so fortunate. Hippies do this when they travel with no money.
Someone who gas jugs... AKA sitting at or near a gas station and watching for someone filling their vehicle so you can walk up with your gas jug and ask them for some gas while they are already gassing up. Repeat as needed.