Yes, about 25 years ago. I'd been having some unexplained gripes that lingered for months, and my doctor decided he'd better take a look. I don't remember much about the prep, but it must have been pot.cit or similar - horrible stuff, but today's PEG concoctions are worse. So I went to a local hospital and duly put on the 'gown of shame' in which it is impossible to maintain even a semblance of dignity. Frankly, total nudity would not be worse!
Once on the table, with what looked like an overblown white sausage of barium (they told me it was 2 litres) threatening me, the nurse inserted the nozzle and inflated the cuff. That was nice; but I really wasn't at my sexual peak... Then came the barium, dull and heavy in my bowels, but not at all crampy. After about half the barium was in, they announced that this would be a double contrast barium/air enema, and proceeded to blow me up like a football. That was nice, too. But what really sticks in my mind is that they had me strapped to that exam table better than a top gun in an F-15. I soon found out why as they proceeded to flip me every which way: stand on your feet; your head, your left and right sides. Hang upside down from the table (no kidding) and pull out of the loop with an Immelmann turn. Barrel roll. Head over heels, and on and on! I tell you, that barium got chased around by the air in me until there was nowhere it hadn't been. I have been on fairground rides that were more exciting, but none of them offered me an enema to go with it!
Finally they let me go to the toilet in the exam room. I guess they were used to the sounds of an air-and-barium fill going down; but I found it embarrassing. I soon got over that, as the extreme difficulty of getting rid of it all became apparent. Of course, one of the prep drugs they give you is an antispasmodic, which does a pretty good job of paralysing the colon. That's why there are no cramps; but then you can't shift the enema. I persevered, with standing up, squatting with my head down, twisting my body and kneading my abdomen. Even so, I I think I got only half of it out. I remember taking a plain enema that night, by which time the barium had lost most of its water by osmosis. It was like shitting cement aggregate.
Do it again? With a bit of luck I might die first.