Traffic bosses are investigating how pranksters altered a set of pedestrian lights to show a couple making love whenever they turned green.
The lights in Nimwegen, Holland literally stopped the traffic when passers by stopped to gawp at them during rush hour.
One officer said: 'People kept pressing the button to see the couple having sex and of course every time they did, the traffic had to stop suddenly. We had quite a lot of rear end shunts from drivers who were too distracted.'
Transport officials are investigating how computer hackers managed to get into the town's traffic light system to manipulate the image. A Town Hall spokesman said: 'We are looking at who had access and opportunity.'