Yeah, its entirely unpleasant. I remember having it. Well, sort of. I remember waking up on the way home. Oh, I'll tell you what they didnt tell me. They have to use air to open your intestines enoug hto get a good look. This means what you think it does.
In any event. Its over relatively fast. Try not to freak out. But even if you do, you'll be drugged up enough that it wont cause problems.