Twinkle, twinkle, there's a ghost in the nursery

There's a ghost in the nursery. I think it lives in the musical Tigger that lives on the shelf in The Little Ninja's bedroom. Because nobody touches that thing and still at random moments during the day and night, it plays "Twinkle, twinkle, little star". Like just a minute ago. I am the only one in the house and I am sitting in the next room. I definitely did not press on the tigger. Or like last night when I was studying and everyone else was sleeping. No one is touching the thing, yet it sings all by itself. It's creepy, I tell you.

I think the next step in my investigation (or ghost-busting, if you will) is to remove the batteries and see if it still sings. Although to be honest I think I would totally freak out if it did, so maybe it's safer to just leave the batteries in and call it a fluke. What do you think?