Pennsylvania

a man's bank account was erroneously credited with a million dollar. The man bought a yacht and a lot of stock. By the time the bank realized their error the man had made hundreds of thousands of dollars on the stock that he purchases.

The bank, however , demanding not only all of the original cash be re-paid but also the profits on his investments. The court upheld the banks demands.

(I may be off a bit on the exact amounts of money, but you get the picture)