“50p”, said the bus conductor.
Hamish thought this was a bit much, so he decided to run behind the bus for a few stops.
“How much is it now?”, he gasped.
“Still 50p”, said the bus conductor.
Hamish ran three further stops behind the bus, and was barely able to ask the bus conductor again what the fare was now.
“75p”, said the bus conductor.
“How could that be?”, asks Hamish.
“You are running in the wrong direction”, replies the bus conductor.
Image used under a Collective Commons License from: https://commons.wikimedia.org/wiki/File:First_Glasgow_40743_on_23.JPG