A teenager with no driving licence took a car without permission and drove it into a garden fence in Hornsby Road, Grantham.
Kamil Myca, of Grantley Street in Grantham, admitted aggravated vehicle taking, driving without a licence and driving without insurance.
The court heard how he was a back-seat passenger with a friend in a car driven by another man. When they parked up, Myca and his friend asked if they could stay in the car to listen to some music.
The owner of the car left the keys in the ignition so 18-year-old Myca decided to drive it himself.
Andrew Coley, defending, said: “He was not intending to drive the car very far but unfortunately he was not in control of the vehicle and collided with a nearby fence.
“When I asked him if it was boredom which had caused this he said, with refreshing honesty, ‘no, it was stupidity’.”
Mr Coley said Myca, who was 17 at the time of the offence, had drunk one beer which he suggested may have acted as a “disinhibitor”.
The court heard the estimated damage caused was around £350 for the fence and £500 for the car.
The case was adjourned until February 11 for pre-sentence reports to be prepared by the Probation Service.