When a piece of electronic equipment no longer works because someone let the "factory smoke" out. You see, every electronic device is built with factory smoke inside. If you or someone else were to damage it (water, physical damage, etc.) and let said smoke out, that equipment will no longer work.
Guy1: My digital camera stopped working. I spilled my drink all over it, and it started smoking.
Guy2: Oh, you let the factory smoke out. Looks like it's time to get another one.