I've had plenty of strange experiences when I was young. As a child, both me and my brother loved our little stuffed animals, and we'd go to bed with them every night. And, while my "teddy bear" was actually a little brown stuffed dog, my brother's teddy bear was one of those Bubba Bear toys, basically a stuffed animal with an electronic voice box inside that would make it talk whenever you squeezed it's paws.
Late one night, we were both deep sleep when the two of us were awakened by a loud sound coming from his side of the room. By this time, he'd had the stuffed bear for a while, and though I was still firmly latched onto mine, my brother had already started to outgrow his. At least, I'd assumed as much, since he started leaving it on the bed shelf instead of keeping it in the covers with him.
At first, either of us knew what had caused the sound, until we heard it again, coming from his talking bear. It was talking on it's own, speaking it's usual lines and dialogue, but without being activated or squeezed. This had never happened before, so my brother and I were understandably frightened. After it happened again, my brother grabbed the toy and opened up its back, flipping the switch to turn it off. And that seemed to be it...for a while.
Later that night, we were awoken again when the toy started talking by itself, it's voice loud and distorted, almost as if the electronics inside were malfunctioning for no reason. My brother and I exchanged a look of surprise and fear as we heard it continue talking. It was still saying the exact same things it's said dozens, maybe hundreds of times, only now it was terrifying as our young minds processed it. A scary electronic voice emerging from a familiar friend, talking in the darkness, seemingly beyond our control.
The voice became more distorted, almost raspy, when my brother grabbed the toy and shook it, though that did nothing to stop it. Finally, he opened the back and pulled out the batteries, and tossed the toy to the ground in sheer terror. It was quiet again, but neither of us could sleep for the rest of that night, as we both were convinced that it would speak again.
We had never had any trouble with it before that night, and we never had any trouble with it afterwards either, even after putting the batteries back in. After that night, my brother would eventually stuff that toy into the back of the closet, where we promptly avoided it for the rest of our childhoods.
And yep, this is a true story.