A would-be robber failed in his bid to raid a Japanese bank after asking staff for tips on how to carry out the crime, according to the Reuters news agency.
Unlike his knife, the would-be robber was not too sharp
And as he was escorted out of the branch in Kumagaya, north of Tokyo the man accidentally stabbed himself with the knife he was carrying.
He had reportedly asked the bank cashier: "Any idea how you rob a bank?"
A colleague asking the man to leave noticed the blade protruding from the pocket of his blood-stained trousers.
Police arrested the 58-year-old unemployed man for illegally carrying a weapon into the branch of the Saitama Resona Bank.
"He didn't brandish the knife at anyone... but he injured himself in the leg," a police spokesman said.