Prime Pump
There is a story about a man who takes the wrong road in the desert and has car problems. He walks and finds an old deserted town with a water pump. The pump isn't working. As he was sitting there he saw a piece of paper in an old bucket which tells of a bottle of water hidden under a rock.
There is good water in the pump--but it needs to be primed with the bottle of water. If the traveler drinks the water he won't have enough to prime the pump. Which will he do?