It started completely by accident.
I was walking from the garage through the kitchen and on my way to the bathroom and as I passed by my older sister Micah who happened to be bent over moving her clothes from the washer and into the dryer, for no reason at all and with no premeditation, I smacked her big ass. However, my hand didn't land on either cheek; it landed almost perfectly in the middle.
Micah emitted an 'Ooof' and as she was straightening up quickly, she bumped the back of her head on the upper rim of the dryer's door. She yelped with pain and it seemed to have stopped her from chasing after me.
I was cautious coming back from the bathroom to resume working on my bike in the garage. But, when I passed her again, she turned around quickly but didn't say anything. She only gave me a hurt look. I didn't give it much thought at the time and chalked my luck to the pain in her head which stopped her from retaliating.