A story that ends in just then the principal walked in

I was in a bathroom stall, passing time, waiting for lunch to end. Even after lunch had passed I stay sitting in the bathroom staring at the wall for what felt like eternity. A loud laugh rung in the bathroom, my trance was immediately broken and I jumped slightly. I could tell there was a few people coming in at once. It sounded like a kid was being bullied in the stall next to me, I felt helpless. I didn’t want to just do nothing about it though. I gathered the strength to walk out of my stall and grab the bullies attention, but as I was about to start talking the principal walked in.