A man was arrested recently using a hack at an ATM - apparently if you backspace at the right time, a bug in the software remembered your original entry for the deduction amount, but used your second entry for the dispensing amount. (not exactly, but the results are the same)
Great hack from a pen-test perspective... but he was arrested because he spent several hours at the same ATM with multiple stolen credit cards.... so awful execution.
(Not linking to avoid details)