In 1995, a man deposited a fake advertising check worth $95,093 as a joke, and the bank cashed it unintentionally.

Patrick Combs was a writer based in San Francisco with $200 in his account.
He received a promotional shipment with a fake check printed for $95,093.35.
It was stamped "non-negotiable" in large letters on the front.
He deposited it as a joke.
He fully expected the bank to detect it immediately.
Ten days later, he checked his account: the money was there.
He didn’t touch it.
For weeks, he checked the balance every ten minutes.
It was still there.
He had the bank convert it into a cashier’s check and stored it in a safe deposit box.
When the bank finally found out what had happened, their security team started showing up at his door.
They handed him legal documents.
He returned the money.
In exchange, he demanded a letter signed by the bank acknowledging each of the mistakes they had made.
They agreed.
He ended up becoming a motivational speaker.
He gave talks at nearly 2,000 organizations.
The whole incident, depositing a fake advertising check, was completely legal.
It was the bank’s own mistakes that led to the process.
He never spent a single dollar and left with a letter proving the bank had failed in its only function.