akhliber: It can be pretty tricky, especially as you have to drink it a cup at a time, allowing 15 minutes between downing each cup. The better times, it's just meant feeling really nauseated until the test is done, then running to the restroom to "get the devil out." The more frustrating times have been those where I'm unable to keep the stuff down, which means starting over with the first cup and timer each time it comes back up, until eventually I hold it all down long enough. Fortunately, there has only been one time where I've been sick more than once during said procedure... but I've seen others at the hospital having a much worse time with it.
Most times I've been lucky enough to hold it down for almost precisely long enough to finish the scans and get to the bathroom before things get ugly. :)
Also, it's frustrating to be handed a cup of the stuff, to say something nerdy like, "ooh, it's what we do to chemists when they die!" and to have the nurse look at me like I'm crazy... "why would we give a dead person something to drink?" Gah!
I remember gagging through an entire cup of the stuff. When I started my second, I was shaking so badly that I couldn't keep the cup steady in my hand, and started spilling it. Being the wuss that I am, I was unable to finish all of it (I couldn't even drink that much
water in that amount of time) and they did the test without the full amount of Barium in me.
With other scans, I had to drink a much more pleasant liquid that wasn't too different from Gatorade. Significantly easier :-)