I was getting prepped for a prostate biopsy a few years ago. I bragged to the nurse that I fell asleep during a root canal once, making light of the biopsy. She stopped right up, looked me square in the eye and said with a stern voice ..... "You won't sleep through this." She was right.
It was like someone shoved one of those foot operated dandelion pullers up my butt and was taking out chunks with every bite.