Once upon a time we bought our little daughter a book with an electronic gizmo molded into the back cover. Whenever you moved the book it would play Jingle Bells. It was so sweet. Then it got old but in the way of little kids she misplaced the book and had enough other books that she didn't really miss it.

But we couldn't miss it for long. For months a muffled Jingle Bells would sound from beneath the couch cushions or under a chair. Then it would get shelved. And found. And then the song would come from yet another location. And the sensitivity of the device increased so that the song would come out at the slightest provocation.

AND IT HAD NO OFF SWITCH! AND THE BATTERY LASTED FOREVER!