Hampshire police in the UK thought it would be a good idea to advertise on the rear of a bus. Their planning did not take into account the location of the exhaust pipe.Source: 1, 2, 3 & 4.
Nicotinell - Feel like quitting?
Quitsmoke.us - What we see when you smoke.
The world can't take anymore CO2. Members of the BUND (the German Friends of the Earth) put globe-balloons on exhaust pipes of cars in Berlin. The exhaust gas inflates the balloon.
Another advertisement on similar lines from the World Wildlife Fund.
This new advertisement from the British Friends of the Earth (FOE) is aimed at students, the least green of all demographic groups.
Print Advertisements Using Illusions.
Creative Advertisements With Fruits & Vegetables.