The authorities said that a bemused witness on Sunday evening reported a car was driving on a county road outside of Bremervörde west of Hamburg with a six-metre-long rope pulling the tub.
"There was also a passenger in the tub sitting on a cushion while wearing a motorcycle helmet," the police said in a statement.
Sparks flew as the tub skidded along the pavement behind the car with Bavarian number plates.
Alerted to their dangerous road shenanigans, the police stopped the duo and promptly started criminal proceedings. But the authorities said there was no apparent damage to the road.