This has happened to me more than once, I'm afraid. Some developer/project manager/self-proclaimed expert who says, "Well yeah, bugs are bad. But I mean, they've never killed anyone."
Guess again, Scooter. Wired just announced the top ten worst software bugs in recorded history (Read the information for yourself.) Among the recorded info is included a radiation therapy software application that accidentally killed eight people because the doctors using the software were unaware what their actions would do by "modifying" the software's output.
Yep. Computer software is in the cars you drive, the systems of the cities you sleep in, the planes you travel in and the hospital equipment used to save your life. And it could potentially kill you.
But don't worry. We're here to protect you. We're QA. Sleep tight.