The end result of having to drink horrible, horrible gloop as part of bowel preperation for procedures such as colonoscopy (also known as Geting An Anal Probe). You end up spending much of the night shitting so much that one is surprised at just how full of shit you really are, hence The Great Shittening.
Tonight is The Great Shittening. I have to drink that horrid gloop so as to have a clean bowel for my anal probe tomorrow.
by RTM 1963 October 16, 2017