Oh, you poor thing! I was fearing the prep in the worst way too.
Let me tell you: this is not as bad as a bad bout of diarrhea or an intestinal bug. It is much, much milder than that. Everyone I have talked to that used the OsmoPrep had no intestinal cramping (which is the worst part of a diarrhea bug, isn't it). It is very gentle. You just will need to go a lot. To be honest, when I did go each time, it wasn't a huge amount, wasn't explosive, wasn't a big deal. Just more of an inconvenience. Each time you go, it becomes more and more watery, until in the morning, it is really just pure water trickling out.
The most uncomfortable part for me was that sometime in the middle of the night, I got VERY thirsty and I had to get up and drink and drink and drink. The OsmoPrep, as well as the liquid solutions, are very salty and they make your thirsty. Have you ever gone out and eaten and really junky, salty meal (something like a salty pizza or country ham) and then just been thirsty for awhile. That is what I felt like. That was the most annoying part. Oh, and my "bum" was sore that morning.