Your sister Jane is 17, so younger than you because you're 19, and well, you two were pretty different, which was to be expected since she's often shy and stuff. But you loved being dangerous, and you argued a lot because Jane and her friends were always checking out your motorcycles and things like that, and it really annoyed you. But whenever you did anything with her, you always got in trouble because, well, you're the older one... typical.
What you didn't know, though, was that once, while you were sick in bed, your sister had been messing around with your motorcycle, and now there's a small scratch on your motocross bike. New tires, everything. And you got really angry when you found out... and you immediately drove to your sister's school with two of your friends.
"You drove onto the grounds and angrily got off, and Jane was startled because you always came to tease her."