Yes, I encountered one for the first time in the bathroom of a holiday let and, having no idea what it was, got very confused as to how I was supposed to turn i

Yes, I encountered one for the first time in the bathroom of a holiday let and, having no idea what it was, got very confused as to how I was supposed to turn it off. Fortunately we had an experimental nuclear physicist in the party who was able to explain that turning the light off would actually be a very bad idea.