Ben Azarya, 14, was travelling in Oxenholme, Cumbria when a man's spray paints fell out of his rucksack and onto the floor.
Kind Ben picked up the equipment and handed them back to the chap.
He probably thought nothing more of it but the bloke then pulled out a copy of Banky's iconic The Flower Thrower and signed it, before handing it to the teen!
Ben was quoted in the Daily Mail saying: "He said 'Do you know who Robin Banks is? I said no and he said: 'This will be worth about £20,000 – have a good life, brother.'"
Robin Banks is a name that has been linked to the anonymous artist in the past.
The lucky lad described the mysterious man as: "White, in his late 40s. He was wearing scruffy clothes and he had a black, fluffy hat which looked really old."
There was also a gas mask and spray paints inside his rucksack.
Ben's mum, Jan, is now trying to get the print authenticated. And if it's the real deal, the schoolboy plans to sell the art.
He said: "I will probably spend about £1,000 and get a new phone and save the rest."
It just shows, being helpful really does pay!
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