A man is stuck in a traffic jam on the Embankment near Westminster. Nothing is moving. Suddenly, a man knocks on the car window.

The driver rolls down the window and asks, "What's going on?"

"Terrorists have kidnapped the members of parliament and they're asking for a £100 million ransom, otherwise, they are going to douse them all in petrol and set them on fire. We are going from car to car collecting donations."

"How much is everyone giving, " the driver asks.

"It varies but on average about a gallon."