Inhabitants of an apartment block in Bavaria, southern Germany, who called police to investigate the relentless buzzing of their doorbells late at night were surprised to find the culprit was not a teenage prankster as they had suspected, but a slug.

The slug had been sliding up and down the bell plate, creating havoc in the building and tearing angry residents out of their beds long after midnight when they could not sleep for the noise.

At first they had suspected the so-called klingelstreich (bell prank), a sometimes popular pastime among German youths. Ding dong ditch, knock-a-door run, or knock-down-ginger as it is variously referred to in English, it typically involves children or youths ringing on a doorbell then running away before they are caught.

But when the ringing continued even after the arrival of two police officers, despite the fact that no one was at the door and a motion detector had failed to activate, a closer look at the metal bell plate revealed the presence of the slug, or nacktschnecke in German – literally a “naked snail”.