A Demon In A Hard Place

This encounter happened back when I was in middle school. I was inside of a locker room at the time and I and the rest of my class were changing out of our gym clothes and preparing to head home. One of my classmates had been planning what he considered to be a "great prank" and schemed with another one of my classmates to summon a demon inside of the locker room. I had heard of their plans a week before but had my doubts as to whether or not they would be able to summon a demon but had no idea how serious my classmate was about summoning this demon. I was rushing to finish getting dressed, so I entered one of the bathroom stalls so I could relieve myself and quickly change clothing inside of the stall. My classmate entered the bathroom section of the locker room and pulled out a Necronomicon he had sneaked inside of the room. He signaled over to his friend to shut off the lights and plunged the entire room into darkness. I heard my classmate begin to shout