A couch surfer towed behind a hatchback around steep Dunedin streets ''failed to engage the brain'', police say.
Motorists were stunned to see a man sitting on a couch and holding on to the rear of the vehicle as it left a trail of sparks behind him.
The Monday night incident was captured on film by a shocked motorist, who saw the female driver with the unusual trailer at a stop sign in Heriot Row.
The motorist, who declined to be named, filmed the vehicle going up London St. It later turned into Stuart St during peak traffic.
The man remained clinging to the back of the car while another woman sat in the rear seat of the vehicle.
The man ''was laughing the whole time''.
His couch-surfing journey ended near Otago Boys' High School in Arthur St, about 5.30pm.
''I think the sparks might have been what stopped them.''
The motorist said he later saw the trio load the coach on to the roof of the vehicle.
The man was hanging out the window, holding on to the couch, as the vehicle went down Arthur St and into Elm Row.
Acting Senior Sergeant Jared Kirk, of Dunedin, who viewed the video on odt.co.nz, said: ''It never ceases to amaze me the lunacy of some individuals who have failed to engage the brain.
''The risks there are obvious to the people involved ... and other motorists and pedestrians. I mean, what would happen if someone had to slam on the brakes in an emergency?''
Police relied on the public's help to report such driving behaviour, he said.
Penalties could range from infringement notices being issued to possible court appearances.