Some time ago I was fannying about with some LED strips and a transformer, i'd pretty much forgotten about it and shoved the lot in a cupboard.
More recently the missus had LED lights in the shop window, I didn't immediately put two and two together until we were casually chatting about them, the penny dropped and I asked what was powering them.
"That transformer you got..." she said, much to my alarm. It was sitting on the window ledge in the shop front.
I removed it but you'll notice it has since passed a PAT test.