The anus has lots and lots of nerve endings. And pepper spray can cause chemical burns. She could have really hurt him. Though the other pranks he played on her were mean, viscous & expensive. He deserved it. Water will make it worse. You want to cleanse it with milk or dairy products. Yogurt would have been good. The acids in the milk products would nutrilize the pepper.
That would mean he didn't use it
https://www.youtube.com/watch?v=ZnAN1X6OQGE&list=PLnIbmU22rvhjydkOO6ZCVoHEufnM6Jm6p&index=2