At the defibrillator company I was seated where I'd overhear conversations among other engineering groups. One day I heard one analog guy arguing with a DSP PhD about some filtering issue.
Since I knew what signal they were talking about, and was able to program the LCD display, I turned the defib into an oscilloscope and showed them the response to a step input. Lots of ripple. That answered their question.
Five minutes unplanned work to solve a problem that would have taken them days.
