Long story short, prank gone wrong and I broke my sister's arm.
Short story long, when I was eight years old I was super into this prank TV show that came on every Thursday night (I still remember sniff). These were the days before prank channels on YouTube, everyone… But anyway, I wanted to be as cool as the people on the TV show. So the next morning I woke up earlier than my sisters (three girls shared one room, with a bunk bed and a twin bed). I slept on the bottom bunk at that point, and I thought it'd be funny to move the ladder from one side of the bed to the other so that when the sister on the top woke up, she'd try to climb down the ladder and see it was missing. I envisioned her being like, "Oh no! WHERE'D THE LADDER GO?!?!" and I thought it would be freaking hilarious. What ended up happening was, she woke up, sat up like a robot, swung her legs over the side, and just slid to the floor with a thud. It was the weirdest thing. I thought it was crazy unfair how weirdly she woke up that morning (at the time I wanted to scream that it wasn't my fault she didn't notice that the ladder wasn't there XD). But she broke her arm from the fall.
The worst part of it is that the day before, she had just gone shopping for her first season of soccer ever (she was seven at the time), and was super excited and took a bunch of pictures in her soccer stuff. So her first season of soccer was ruined. PLUS, my other sister kind of half woke up while I was "setting up" the prank and said, "That's not a good idea," and I replied, "What do you mean, it'll be fine." UGH. I was forced to be the good arm for my sister while she healed.
I wasn't allowed to watch the prank TV show ever again. :'(