I used to believe that if I poured water on anthills the ants would drown, so one day I went out with a bucket full of water and poured it over every single anthill I could find hoping they'd become extinct.
My sister got a plastic kitchen on her bday where she and my younger sister would play. They'd put water in the plastic pans and drink it after "heating it" in the little oven. One day I had the great idea that we could make the oven actually work, so I stuck some matches inside the oven and lit them up. The sticker that had the picture of the oven caught on fire and the back of the oven melted. And that was the last time I was allowed to play with the plastic kitchen.
That the girls bathroom had couches and special interior decorating, etc.
Also, From the age of 9-15 i was convinced due to my dreams that some one would one day break into our house and kill my family so I would lock my door at night and push my dresser in front of the door sometimes and had an escape route planned out of my window for when that day came.
I believed that whole 'if you swallow gum you'll get a gumball in your stomach and it never gets out' story my mom used to tell me.
I've never swallowed gum.