@Ruggercat68, I went through a high enema one time after the doctor didn't like the looks of my endoscopy. Believe me, I didn't exactly volunteer for the treatment, but he wanted to take another look at something and needed a cleaner picture.
It really wasn't as bad as I thought. The worst part was getting the entire amount of fluid into my colon. I felt like I had to go to the bathroom, but it wasn't like cramping up from food poisoning or anything. The wait was no fun, but it wasn't unbearable.