I went to Germany a few years ago, and after hours on the train, really had to pee.

But the public restrooms would only take German coins, and were particularly designed to avoid sliding under the door, so off I went to my destination.

When I got there, they all said, just pee on the wall, everyone else does.

The city of Hamburg has erected signs around the city reading “Don’t pee here. We pee back.” A public awareness campaign video shows CCTV footage of a stream of men on the way home from a drunken night out stopping to relieve themselves in the street. Then the video introduces the city’s secret weapon.

In the fight against the scourge of urinating drunks, the local St Pauli neighbourhood association has begun painting its walls with water-repellent paint, similar to the type used on ships.

The association told a number of outlets that when liquid hits the walls it rebounds with “almost the same force”. Handy graphics spell it out for anyone still confused.