A Lucky Las Vegas Gambler.
The stall happened to be open, so he used the dime in a slot machine and hit the jackpot. He took his winnings and went to the blackjack table and turned his small winnings into ten million dollars.
Wealthy beyond his wildest dreams, Ned went on the lecture circuit, where he told his incredible story. He told his audiences that he was eternally grateful to his benefactor, and if he ever found the man he would share his fortune with him.
After months of lectures, a man in the audience jumped up and said, "I'm that man. I was the one who gave you the dime."
"You're not the one I'm looking for. I'm looking for the guy who left the stall door open!"