The cars (electrons) come out of the parking garage exit (- terminal), enter the roadway (wires), and start driving (current).
If there's a break in the roadway, the cars can't drive, unless there's a flat (conductive) surface to go to. Also, the parking garage won't let a car out unless another one comes back, thereby creating the necessity for a closed circuit.
More applicable items:
Road width = resistance
# of cars passing per second = amperage
speed of cars = voltage
Gas tank level = battery life