Safety coffins, which had various mechanisms for signaling if you woke up inside of one, were in vogue for quite a while. https://en.wikipedia.org/wiki/Safety_

Safety coffins, which had various mechanisms for signaling if you woke up inside of one, were in vogue for quite a while. https://en.wikipedia.org/wiki/Safety_coffin https://en.wikipedia.org/wiki/Safety_coffin