The German man, who has lived in Denmark for nearly 50 years, walked into a Sydbank branch in the western town of Viborg on Thursday wearing dark glasses and carrying a cane. Pointing a water gun at the teller, he politely asked her to give him a bit of money.
"Don't worry," he said, according to media reports. "I don't shoot people."
He left the bank with a plastic bag filled with about 30,000 kroner (€4,000, $6,100), but only managed to walk some 300 metres (985 feet) before he was stopped by police. By that time, his booty had become worthless after an exploding cartridge placed in the bag by the bank clerk exploded, spraying the money – and his clothing – with red ink.
The man planned the hold-up after he overdrew his account when redecorating his new apartment in a retirement home and his bank refused to set up a repayment plan for him.
Police said it remained unclear whether the man had robbed his own bank. On Friday, the man happily accepted being sent to jail, telling the judge: "I don't want to return to my apartment. I'm too ashamed."