That was just wicked... I remember being once in that situation. I was chained to the radiator in the hallway entrance of my dommes's appartment and had to hear the shouts and screams coming from the bedroom, where she was flogging another sub. I knew the other girl, and I considered her to be tougher and more experienced at taking pain than I was. Knowing that my turn was coming made me dizzy with fear.

By the time I was tied to the piano bench where I was to be flogged, I was shaking almost out of control. The whipping was almost gentle, (I realized later) but my apprehension made it so terrible that I screamed my head off as if I was being skinned alive. The most horrible touch came afterwards, when the other sub was ordered into the room and made to show her naked body to me.

She did not have one single bruise or welt on her body! The sounds I had heard and that made me panic so much had been my mistress using her cane on the padded piano bench and the other sub play acting and screaming to match every stroke!
Talk about head games!