Fecal vomiting or antiperistalsis is a kind of emesis in which fecal matter is expelled from the intestines into the stomach, by spasmodic contractions of the gastric muscles, and then subsequently forcefully expelled from the stomach up into the esophagus and out through the mouth and sometimes nasal passages. Alternative medical terms for fecal vomiting are copremesis and stercoraceous vomiting. It was also referred to as miserere in medieval times.
Not to bump one of the most disturbing words in the English language back to the top, but I've been finding more rhetorical uses for this word every day. Along with copremetic, which I assume would be the adjectival form or whatnot.