costly in paper
We had a cobol report that had a slight bug in the code. It sent the malformed report to the printer. 18 boxes of paper later (at 5 reams per box) the operator decided that something was probably wrong and killed the print job. Next morning the print was delivered back to the office on a large overflowing trolley, fortunately it wasn't my bug. It was simplex printed so we had plenty of spare scrap paper for the next 10 years.