Auctioneers expect the sketch to sell for £5,000
A taxi driver was given a doodle on a scrap of paper as an unusual tip, but as the customer was artist Damien Hirst it could be worth £5,000.
Jon Horsley, 40, gave the drawing to his son LJ, who hopes to become a film-maker. The 15-year-old has decided to sell it to fund his ambition.
The sketch, depicting Hirst's famous pickled shark and jewelled skull sculptures, is now up for auction.
Mr Horsley said he hoped it would help his son succeed in the media.
The resident of north-east London said: "I picked up Damien Hirst about two years ago.
"My son, who was doing his GCSE art, said, 'why didn't you make him give you a drawing?'
"I said that if I ever picked him up again I would ask."
Mr Horsley picked up the multi-millionaire artist again six months ago.
"That time Mr Hirst did a drawing for my son," he said. "If I'm being honest I think he should keep it.
"But if it gives him a leg up with film-making it will be worth it."
LJ hopes to spend any money from the sale at Dreweatts & Bloomsbury auctioneers to buy a new camera.
The auctioneers expect it to make £5,000.
The record price for a Damien Hirst work is £10.34m.