Children are so random and impulsive some of these things.
I was mostly quite a good child but I can think of a couple of things to put in.
One of my earliest memories. I had a set of animal dominoes made out of cardboard. I was playing one day in my bedroom and I must have done a wee in my potty, or perhaps my little sister had, because I remember looking at this potty full of wee and the domino and thinking "I wonder what would happen if I put it in there?" I put it in and immediately forgot all about it.
Some time later I was playing downstairs and I can remember my mum suddenly appearing in the doorway holding the soggy domino and the potty and asking "What's this?" At first I was fascinated and remember looking at how all the paper layers had curled up away from each other. Then she explained that she would have to throw the whole set away because it was ruined and I was very upset and cried.
Around the same age I suppose. I have no memory of this, but my mum told me about it. We had some gigantic beanbags which had the Heinz Beans and Tomato Soup logos on them. You can guess what I did - I opened one up and pulled all the filling out - it was filled with lots of tiny chunks of yellow and green foam. Apparently, I spread them all around the room and when my mum opened the door I said "Look, I'm sailing in my boat!" she had to instantly close the door again
we found bits of the foam around for years.
I did get karmic payback for this as my own DC did the same thing except that modern beanbags have polystyrene balls which instantly static charge to everything and repel each other and are a nightmare to clean up. DS3 was about 18 months, was inexplicably naked when it happened and decided to just roll around in them on the floor, which ended up with him wearing a coat of polystyrene balls. Everywhere! They were clinging to his eyelashes. I have a hilarious photo of him where it looks like we have vajazzled him.
I did unintentionally torture ladybirds as well - we had this sandpit with a lid that collected rainwater and had little roads built into it so we made them "swimming pools" there were new houses being built near us and we often found tiny little squares of foam around, which reminded me of swimming floats so I used them as ladybird boats. They were free to leave any time, they did get to the other side OK and we thought we were making them fun things but of course they probably can't actually swim and were likely frightened
we did this for ages, an entire summer if not more than one. Any time we found a ladybird we'd bring it to our torture camp paradise?? I let them run around in my Polly Pocket houses as well, they didn't seem to mind this.
I used to hit my sister over the head with a Playstation controller when she annoyed me, but she used to do the same back to me, so maybe that was just normal sibling bickering. We are fine, I think.